425

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the
Securities Exchange Act of 1934

Date of report (Date of earliest event reported): January 12, 2012

Aon Corporation

(Exact Name of Registrant as Specified in Charter)

Delaware	1-7933	36-3051915
(State or Other Jurisdiction of Incorporation)	(Commission File Number)	(IRS Employer Identification No.)

200 East Randolph Street, Chicago, Illinois
(Address of Principal Executive Offices) 60601
(Zip Code)

Registrant’s telephone number, including area code: (312) 381-1000

Not Applicable
(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

xWritten communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

oSoliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

oPre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

oPre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 1.01 Entry into a Material Definitive Agreement

Announcement of Reorganization; Entry into Merger Agreement

On January 13, 2012, Aon Corporation, a Delaware corporation (the “Company”), announced a plan to reorganize its corporate structure and relocate its corporate headquarters to the United Kingdom.  Under the plan, Chicago will continue as headquarters for operations in the Americas.  If consummated, the reorganization would result in stockholders of the Company holding shares in a newly-formed public limited company organized under English law.  In connection with the proposed reorganization, the Company entered into an Agreement and Plan of Merger and Reorganization (the “Merger Agreement”) with Market Mergeco Inc., a newly-formed Delaware corporation (“Mergeco”) and wholly-owned subsidiary of Aon Holdings LLC, a newly-formed Delaware limited liability company (“Aon Intermediate”) and wholly-owned subsidiary of the Company.  The Merger Agreement provides, among other things, that, upon the terms and subject to the conditions set forth in the Merger Agreement, Mergeco will merge with and into the Company, with the Company surviving the merger as a wholly-owned subsidiary of Aon Intermediate (the “Merger”).  Aon Intermediate will become, in connection with the Merger, a wholly owned subsidiary of Aon Global Limited, a newly-formed private limited company incorporated under English law which, prior to the effective time of the Merger, will re-register as a public limited company named “Aon plc” or a similar name (“Aon UK”).

If approved by the stockholders of the Company, subject to certain conditions and upon consummation of the Merger, each issued and outstanding share of the common stock of the Company, par value $1.00 per share, will be converted into the right to receive one Class A Ordinary Share of Aon UK, nominal value $0.01 per share.  Upon completion of the Merger, Aon UK, together with its subsidiaries, will own and continue to conduct the Company’s business in substantially the same manner as it is currently being conducted by the Company and its subsidiaries.  Aon UK is expected to remain subject to the same U.S. Securities and Exchange Commission (the “SEC”) reporting requirements as the Company is currently and will file an application with the New York Stock Exchange to have its Class A Ordinary Shares listed there.

The foregoing summary of the Merger Agreement and the transactions contemplated thereby contained in this Item 1.01 does not purport to be a complete description and is qualified in its entirety by reference to the terms and conditions of the Merger Agreement, a copy of which is filed as Exhibit 2.1 and incorporated herein by reference.

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

In connection with the Company’s entry into the Merger Agreement, on January 12, 2012, the Company or one of its subsidiaries entered into international assignment letter agreements (the “International Assignment Letters”) with certain of the Company’s named executive officers to provide such officers with relocation benefits in connection with their relocation to the United Kingdom in connection with the Merger.  For more information, please see “Interests of the Directors and Executive Officers in the Merger” in the registration statement on Form S-4 (the “Registration Statement”) filed on the date hereof by Aon UK with the SEC.

The foregoing summary of the International Assignment Letters contained in this Item 5.02 does not purport to be a complete description and is qualified in its entirety by reference to the terms and conditions of the International Assignment Letters, copies of which are attached as Exhibits 10.1,  10.2,  10.3 and 10.4 and incorporated herein by reference.

Item 7.01 Regulation FD Disclosure

On January 13, 2012, the Company issued a press release announcing the proposed plan to change its corporate structure.  A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K and incorporated herein by reference.

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Additional Information

In connection with the proposed reorganization, Aon UK has filed with the SEC a registration statement on Form S-4 that included a preliminary proxy statement/prospectus, and each of the Company and Aon UK may be filing with the SEC other documents regarding the proposed reorganization.  At the appropriate time, the definitive proxy statement/prospectus regarding the proposed reorganization will be mailed to Company stockholders. Before making any voting or investment decision, investors and stockholders are urged to read carefully in their entirety the definitive proxy statement/prospectus regarding the proposed reorganization and any other relevant documents filed by either the Company or Aon UK with the SEC when they become available because they will contain important information about the proposed transaction.  You may obtain copies of all documents filed with the SEC regarding this transaction, free of charge, at the SEC’s website (www.sec.gov) or from the Company and Aon UK by accessing Aon’s website at www.aon.com under the heading “Investor Relations” and then under the link “SEC Filings” or by directing a request to 200 East Randolph Street, Chicago, Illinois 60601, Attention: Investor Relations.

The Company and Aon UK and their respective directors and executive officers and certain other members of management and employees may be deemed to be participants in the solicitation of proxies in respect of the proposed transaction. You can find information about the Company’s directors and executive officers in its definitive proxy statement filed with the SEC on April 8, 2011. Other information regarding the participants in the proxy solicitation and a description of their direct and indirect interests, by security holdings or otherwise, will be contained in the proxy statement/prospectus and other relevant materials to be filed with the SEC when they become available. You can obtain free copies of these documents using the contact information above.

Item 9.01 Financial Statements and Exhibits

(d)           Exhibits:

Exhibit Number	Description of Exhibit
2.1	Agreement and Plan of Merger and Reorganization by and among Aon Corporation and Market Mergeco Inc. dated January 12, 2012 (incorporated by reference to Annex A of the Registration Statement on Form S-4 filed by Aon UK on January 13, 2012 with the Securities and Exchange Commission).
10.1	International Assignment Letter with Gregory C. Case, dated January 12, 2012.
10.2	International Assignment Letter with Christa Davies, dated January 12, 2012.
10.3	International Assignment Letter with Stephen P. McGill, dated January 12, 2012.
10.4	International Assignment Letter with Michael J. O’Connor, dated January 12, 2012.
99.1	Press Release dated January 13, 2012.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Date: January 13, 2012	Aon Corporation
	By:	/s/ Gregory C. Case
		Gregory C. Case
		President and Chief Executive Officer

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EXHIBIT INDEX

Exhibit
Number	Description of Exhibit
2.1	Agreement and Plan of Merger and Reorganization by and among Aon Corporation and Market Mergeco Inc. dated January 12, 2012 (incorporated by reference to Annex A of the Registration Statement on Form S-4 filed by Aon UK on January 13, 2012 with the Securities and Exchange Commission).
10.1	International Assignment Letter with Gregory C. Case, dated January 12, 2012.
10.2	International Assignment Letter with Christa Davies, dated January 12, 2012.
10.3	International Assignment Letter with Stephen P. McGill, dated January 12, 2012.
10.4	International Assignment Letter with Michael J. O’Connor, dated January 12, 2012.
99.1	Press Release dated January 13, 2012.

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EX-10.1

Exhibit 10.1

Greg Case

Aon Corporation

USA

January 12, 2012

International Assignment – Chicago, Illinois (U.S.) to London, England

Dear Greg,

Your relocation to London is critical to Project Market and will help us realize the benefits of the transaction for all concerned stakeholders.  As you know, the transaction is anticipated to position the company for future growth, improve our financial flexibility, and increase our ability to invest globally in strategic initiatives and talent.

We recognize this assignment will require a significant time commitment, as well as personal adjustment and inconveniences for you and your family. However, we are committed to working with you to ensure that your international assignment is as successful and smooth as possible.

This letter sets out the terms of your assignment and the assistance we are committed to provide in connection with your relocation, consistent with the approval of, and directions provided by, the Organization and Compensation Committee of the Company’s board of directors.

1.Introduction

This assignment is subject to your acceptance of the terms and conditions outlined in this letter, which sets forth the entire agreement between you and the Company regarding your international assignment.  To the extent that anything in this letter conflicts with your current employment terms or agreement, or the Company’s Employee Handbook, this letter, once countersigned by you, will be a variation to your employment terms.  Unless otherwise specified herein, your current employment terms and conditions will remain unchanged for the duration of the international assignment.

2.Employment status

These terms and conditions will only be in effect for the period of this assignment.  During this period you will remain an employee of Aon Service Corporation or Aon Corporation, as applicable (“the Company”).  You will be expected to conform to the general requirements of the Company’s Employee Handbook and any local rules and procedures and relevant legislation.  During the assignment, you will be seconded (loaned) to Aon Global, Limited, Aon’s parent company in London, England.

3.Assignment duration

Your assignment will commence on a date to be mutually agreed on or before September 1, 2012.  The duration of the assignment is expected to be less than 24 months, after which you will return to the Company’s offices in Chicago, Illinois, provided that the Company may, in consultation with you, extend or shorten your assignment according to business needs and/or your personal circumstances. In the event that your assignment is extended beyond 36 months the Company reserves the right to “localize” your terms.

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4.Immigration

Your assignment is conditional upon the Company being able to obtain and maintain the appropriate work permit, visa and/or other authorization documents for you to work and remain in London, England.  The Company will cover the cost of obtaining and maintaining the appropriate work permit/visa for you.  In addition, should you desire and consistent with current policy, the Company will also assist your spouse or partner in obtaining a work permit, visa and/or other authorization documents to work in London.

5.Changes to Compensation Arrangements

The changes to your compensation and benefits package during your international assignment, as described below, are designed to provide you with a level of income and benefits which do not disadvantage you in comparison to those you would have received in the United States. We have also taken into consideration any additional costs that you may reasonably incur as a result of living in London.  Unless otherwise noted below as being a non-taxable benefit, the following benefits will be provided to you subject to income and social taxes.

5.1.Foreign Service Allowance

You will receive an annual foreign service allowance of US$135,000. The allowance will be paid semi-monthly via your U.S. payroll.

5.2.Housing Allowance

During your assignment you will receive an annual housing allowance of US$336,000 (GBP214,020) [monthly allowance of US$28,000 (GBP17,835)].  The allowance is to be used to pay accommodation and furniture rental costs and associated utility costs (excluding telephone and internet access which are personal expenses).  This allowance will be reviewed and adjusted annually to reflect foreign exchange and local market rate variation.  The allowance will paid semi-monthly via your U.S. payroll.

The Company will not be responsible in any way for your current residence in your home location. The payment of your U.S. housing expenses will remain your responsibility.

5.3.Cost of living allowance

You will receive an annual cost of living allowance of US$90,000.  The allowance is intended to replicate your U.S. purchasing power in London and is based on a family size of four.  The allowance will be paid semi-monthly via your U.S. payroll.

5.4.Relocation Allowance

You will receive a one-time relocation allowance of US$80,000 in the first month you are working in London. This allowance is intended to cover all miscellaneous expenses not covered by other provisions included in your relocation package.  All or a portion of this allowance may be non-taxable to you if used to purchase certain goods or services related to the international assignment, as evidenced by receipts.  Your independent tax advisor will provide the criteria.

5.5.“Good Reason” Waiver

You acknowledge and agree that your consent herein to the international assignment, and your acceptance of this international assignment to London and repatriation thereafter, shall not give rise to any right to terminate for good reason (as defined in your employment agreement, if applicable) now or hereafter.

5.6.Income Tax Planning Services

The company will provide you with expatriate tax planning services for the years covered by the international assignment, as necessary.

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6.Hours of Work and Holidays

Your work schedule, work hours and observed holidays will follow the practice in London.

7.Repayment agreement

Should you elect to resign from the Company to work with a direct competitor, during your assignment or up to 12 months after the end of your assignment, the Company reserves the right to require repayment of all expatriate allowances you received in the preceding 12 months.  You agree that the Company may set off any such amounts against any amount the Company owes you on or after termination of your employment.

Should you depart the Company due to mutual consent, this repayment obligation in this paragraph 7 will not apply.

8.Termination of Employment

If your employment is terminated without cause while on assignment, the Company will pay reasonable transportation and moving costs for you and your family to return to the U.S.  For avoidance of doubt, in this instance the company will provide tax planning services for the tax years covered by the international assignment and tax years for which international earnings are taxed by U.K. tax authorities following repatriation.

Should you be terminated for cause or voluntarily terminate your employment without mutual consent, you will bear all relocation and other costs arising after your termination for cause or resignation date.

9.Repatriation Assistance

The Company will pay the transportation and moving cost for you and your family back to the U.S. at the end of your assignment in accordance with the Company’s international relocation policy.

10.Third Party Beneficiary

Each related entity of the Company is a third party beneficiary of this letter, and each of them has the full right and power to enforce rights, interests and obligations under this letter without limitation or other restriction.

11.No Waiver

No failure or delay by any party in exercising any right, power or remedy under this letter shall operate as a waiver thereof, nor shall any single or particular exercise of the same preclude any further exercise thereof or the exercise of any other right, power or remedy.  Without limiting the foregoing, no waiver by any party of any breach of any provision of this letter shall be deemed to be a waiver of any subsequent breach of that or any other provision of this letter.

12.Code Section 409A

We intend that this letter and the benefits provided hereunder be interpreted and construed to comply with Section 409A of the U.S. Internal Revenue Code of 1986, as amended (“Code Section 409A”), to the extent applicable thereto. The time and form of payment of compensation, expense reimbursements and payments of in-kind benefits described herein will be made in accordance with the applicable sections of this letter, provided that with respect to termination of employment for reasons other than death, the payment at such time can be characterized as a “short-term deferral” for purposes of Code Section 409A or as otherwise exempt from the provisions of Code Section 409A, or if any portion of the payment cannot be so characterized, and you are a “specified employee” under Code Section 409A, such portion of the payment will be delayed until the earlier to occur of your death or the date that is six months and one day following your termination of employment (the “Delay Period”).  Upon the expiration of the Delay Period, all payments and benefits delayed pursuant to this

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section will be paid or reimbursed to you in a lump sum, and any remaining payments due under this letter will be payable at the same time and in the same form as such amounts would have been paid.  For purposes of applying the provisions of Code Section 409A, each separately identifiable amount to which you are entitled will be treated as a separate payment.

13.Governing Law

This letter will be construed in accordance with and governed by the laws of the State of Illinois, without regard to the choice of law principles thereof.  Any suit, action or other legal proceeding arising out of or relating to this Agreement shall be brought exclusively in the Federal or state courts located in the State of Illinois.  You agree to submit to personal jurisdiction in the foregoing courts and to venue in those courts.  You further agree to waive all legal challenges and defenses to the propriety of a forum in Chicago, Illinois and to the application of Federal or Illinois law therein.

Please confirm acceptance of the terms set out in this letter by signing below and returning a copy of the signed letter to me.

Sincerely,

/s/ Gregory J. Besio

Gregory J. Besio

EVP, Chief Human Resource Officer

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Employee’s Acknowledgement:

By signing below, I acknowledge receipt of this letter; I accept the terms and conditions contained herein; and I consent to this international assignment.  For the avoidance of doubt, nothing in this letter is intended to diminish my rights under my current employment arrangement with the Company (including, if applicable, my employment agreement with the Company), or any plan or equity-based award agreement, and I will continue to be entitled to the rights and benefits under any such arrangement during this international assignment.  Notwithstanding the foregoing, I acknowledge and agree that my consent herein to the international assignment, and my acceptance of this particular international assignment to London and my repatriation thereafter, shall not give rise to any right to terminate for good reason (as defined in the employment agreement, if applicable) now or hereafter.

I further acknowledge that I have read and agree to be bound by the Company’s tax equalization policy (as set forth on Appendix A).  With regard to that policy, I specifically agree acknowledge and agree that: if I owe any monies to the Company I will make payment of such monies to the Company within 60 days of receiving notification of the amount due; and authorize the Company to deduct (or reduce from my earnings) any amounts owed under this policy from my paycheck where permitted by law.

/s/ Greg Case	January 12, 2012
Greg Case	Date

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EX-10.2

Exhibit 10.2

Christa Davies

Aon Corporation

USA

January 12, 2012

International Assignment – Chicago, Illinois (U.S.) to London, England

Dear Christa,

Your relocation to London is critical to Project Market and will help us realize the benefits of the transaction for all concerned stakeholders.  As you know, the transaction is anticipated to position the company for future growth, improve our financial flexibility, and increase our ability to invest globally in strategic initiatives and talent.

We recognize this assignment will require a significant time commitment, as well as personal adjustment and inconveniences for you and your family. However, we are committed to working with you to ensure that your international assignment is as successful and smooth as possible.

This letter sets out the terms of your assignment and the assistance we are committed to provide in connection with your relocation, consistent with the approval of, and directions provided by, the Organization and Compensation Committee of the Company’s board of directors.

1.Introduction

This assignment is subject to your acceptance of the terms and conditions outlined in this letter, which sets forth the entire agreement between you and the Company regarding your international assignment.  To the extent that anything in this letter conflicts with your current employment terms or agreement, or the Company’s Employee Handbook, this letter, once countersigned by you, will be a variation to your employment terms.  Unless otherwise specified herein, your current employment terms and conditions will remain unchanged for the duration of the international assignment.

2.Employment Status

These terms and conditions will only be in effect for the period of this assignment.  During this period you will remain an employee of Aon Service Corporation or Aon Corporation, as applicable (“the Company”).  You will be expected to conform to the general requirements of the Company’s Employee Handbook and any local rules and procedures and relevant legislation.  During the assignment, you will be seconded (loaned) to Aon Global, Limited, Aon’s parent company in London, England.

3.Assignment Duration

Your assignment will commence on a date to be mutually agreed on or before September 1, 2012.  The duration of the assignment is expected to be less than 24 months, after which you will return to the Company’s offices in Chicago, Illinois, provided that the Company may, in consultation with you, extend or shorten your assignment according to business needs and/or your personal circumstances. In the event that your assignment is extended beyond 36 months the Company reserves the right to “localize” your terms.

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4.Immigration

Your assignment is conditional upon the Company being able to obtain and maintain the appropriate work permit, visa and/or other authorization documents for you to work and remain in London, England.  The Company will cover the cost of obtaining and maintaining the appropriate work permit/visa for you.  In addition, should you desire and consistent with current policy, the Company will also assist your spouse or partner in obtaining a work permit, visa and/or other authorization documents to work in London.

5.Changes to Compensation Arrangements

The changes to your compensation and benefits package during your international assignment, as described below, are designed to provide you with a level of income and benefits which do not disadvantage you in comparison to those you would have received in the United States. We have also taken into consideration any additional costs that you may reasonably incur as a result of living in London.  Unless otherwise noted below as being a non-taxable benefit, the following benefits will be provided to you subject to income and social taxes.

5.1.Foreign Service Allowance

You will receive an annual foreign service allowance of US$120,000. While on assignment, your target annual incentive award will be 150% of the sum of your annual base salary, as in effect at the end of the bonus year, plus your annual foreign service allowance.  The allowance will be paid semi-monthly via your U.S. payroll.

5.2.Housing Allowance

During your assignment you will receive an annual housing allowance of US$252,000 (GBP160,800) [monthly allowance of US$21,000 (GBP13,400)].  The allowance is to be used to pay accommodation and furniture rental costs and associated utility costs (excluding telephone and internet access which are personal expenses).  This allowance will be reviewed and adjusted annually to reflect foreign exchange and local market rate variation.  The allowance will paid semi-monthly via your U.S. payroll.

The Company will not be responsible in any way for your current residence in your home location. The payment of your U.S. housing expenses will remain your responsibility.

5.3.Cost of Living Allowance

You will receive an annual cost of living allowance of US$90,000.  This allowance is intended to replicate your U.S. purchasing power in London and is based on a family size of four.  The allowance will be paid semi-monthly via your U.S. payroll

5.4.School Tuition Allowance

The Company will pay the tuition, application and registration fees for your children from kindergarten through preparatory/high school age to attend an American school, or equivalent, in London.  We estimate the annual cost per eligible child to be US$34,500 (GBP22,000). This allowance will be reviewed and adjusted annually to reflect foreign exchange and local market rate variation.  The allowance will be paid semi-monthly via your U.S. payroll.

5.5.Car Allowance

You will receive an annual car allowance of US$23,500 (GBP15,000) while on assignment in the U.K.  Some or all of this allowance may be non-taxable to you, depending on the extent of your usage of transportation for Company business. This allowance will be reviewed and adjusted annually to reflect local market practice.  The allowance will be paid semi-monthly via your U.S. payroll.

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5.6.Home Leave Allowance

You and each family member that is relocating with you are entitled to one round-trip home leave to return to the U.S. for each complete year you are on assignment.  In addition, any immediate family members (e.g., university aged dependent children) not accompanying you on assignment are entitled to two round-trip flights to the U.K. for each complete year you are on assignment.

5.7.Household Goods Move

The Company will pay the transportation and moving cost of you and your family to London from the U.S. at the beginning of your assignment in line with the Company’s relocation policy for an international household goods move.  You and your spouse or partner may also make a pre-assignment visit to London at Company expense to locate permanent housing.  If necessary, you will be provided with corporate housing for up to 30 days after your arrival on assignment to allow time to finalize your permanent housing. All or a portion of the benefits described in this paragraph 5.7 may be non-taxable to you.

5.8.Relocation Allowance

You will receive a one-time relocation allowance of US$76,667 in the first month you are working in London. This allowance is intended to cover all miscellaneous expenses not covered by other provisions included in your relocation package.  All or a portion of this allowance may be non-taxable to you if used to purchase certain goods or services related to the international assignment, as evidenced by receipts.  Your independent tax advisor will provide the criteria.

5.9.Waiver/Retention Bonus

You will receive a waiver/retention bonus of US$419,976 as consideration, and in exchange, for your acknowledgement and agreement that your consent herein to the international assignment, and your acceptance of this international assignment to London and repatriation thereafter, shall not give rise to any right to terminate for good reason (as defined in your employment agreement, if applicable) now or hereafter.  This bonus will be paid in two equal lump sums: one-half in the month prior to your relocation to London; and, one-half on the 12 month anniversary of the relocation date.

5.10.Income Taxes Payable in the U.K. (Equalization Tax)

It is likely that all or a portion of your earned income during any given U.K. tax year will be subject to tax in the U.K. The Company applies a tax equalization policy (as described in Appendix A) which is designed to ensure the income and social taxes you pay will be no more than what you would have paid had all of your earnings been taxable solely in the U.S.  For the avoidance of doubt, the policy does not provide for the grossing up for U.S. income and social taxes on the relocation benefits described herein.

5.11.Tax Preparation Services

The Company will also provide you with enhanced tax preparation, financial planning and expatriate services for the tax years covered by the international assignment and tax years for which international earnings are taxed by U.K. tax authorities following repatriation at the conclusion of the assignment.

6.Hours of Work and Holidays

Your work schedule, work hours and observed holidays will follow the practice in London.

7.Repayment Agreement

Should you elect to resign from the Company to work with a direct competitor, during your assignment or up to 12 months after the end of your assignment, the Company reserves the right to require repayment of all expatriate allowances you received in the preceding 12

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months.  You agree that the Company may set off any such amounts against any amount the Company owes you on or after termination of your employment.

Additionally, with respect to the waiver/retention bonus only, if you resign for any reason while on the international assignment or the Company terminates your employment for cause (as defined in your employment agreement), you will be obligated to repay promptly to the Company a pro-rata portion of the annual waiver/retention bonus.  The prorated portion to be repaid will be calculated according to the following formula:  (the number of months remaining before the next succeeding anniversary date of the beginning of the international assignment divided by 12) x the USD value of the annual waiver/retention bonus.

Should you depart the Company due to mutual consent, the repayment obligation in this paragraph 7 will not apply.

8.Termination of Employment

If your employment is terminated without cause while on assignment, the Company will pay reasonable transportation and moving costs for you and your family to return to the U.S.  For avoidance of doubt, in this instance the company will continue to provide tax preparation and planning services for the tax years covered by the international assignment and tax years for which international earnings are taxed by U.K. tax authorities following repatriation.

Should you be terminated for cause or voluntarily terminate your employment without mutual consent while on assignment, you will bear all relocation and other costs arising after your termination for cause or resignation date.

9.Completion of Assignment

At the end of your assignment the Company will endeavor to repatriate you into a position consistent with your then current employment agreement, if applicable, and in accordance with your capabilities, interest and career potential.  Your relocation will be managed in accordance with the provisions of the Company’s policy.

10.Repatriation Assistance

The Company will pay the transportation and moving cost for you and your family back to the U.S. at the end of your assignment in accordance with the Company’s international relocation policy.

11.Third Party Beneficiary

Each related entity of the Company is a third party beneficiary of this letter, and each of them has the full right and power to enforce rights, interests and obligations under this letter without limitation or other restriction.

12.No Waiver

No failure or delay by any party in exercising any right, power or remedy under this letter shall operate as a waiver thereof, nor shall any single or particular exercise of the same preclude any further exercise thereof or the exercise of any other right, power or remedy.  Without limiting the foregoing, no waiver by any party of any breach of any provision of this letter shall be deemed to be a waiver of any subsequent breach of that or any other provision of this letter.

13.Withholding and Deductions

While it is anticipated that all or most of your compensation from the Company will be subject to a hypothetical tax deduction rather than actual tax withholdings, all amounts paid pursuant to this letter shall be subject to deductions and withholding for taxes (national, local, foreign or otherwise) to the extent required by applicable law.

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14.Code Section 409A

We intend that this letter and the benefits provided hereunder be interpreted and construed to comply with Section 409A of the U.S. Internal Revenue Code of 1986, as amended (“Code Section 409A”), to the extent applicable thereto. The time and form of payment of compensation, expense reimbursements and payments of in-kind benefits described herein will be made in accordance with the applicable sections of this letter, provided that with respect to termination of employment for reasons other than death, the payment at such time can be characterized as a “short-term deferral” for purposes of Code Section 409A or as otherwise exempt from the provisions of Code Section 409A, or if any portion of the payment cannot be so characterized, and you are a “specified employee” under Code Section 409A, such portion of the payment will be delayed until the earlier to occur of your death or the date that is six months and one day following your termination of employment (the “Delay Period”).  Upon the expiration of the Delay Period, all payments and benefits delayed pursuant to this section will be paid or reimbursed to you in a lump sum, and any remaining payments due under this letter will be payable at the same time and in the same form as such amounts would have been paid.  For purposes of applying the provisions of Code Section 409A, each separately identifiable amount to which you are entitled will be treated as a separate payment.

15.Governing Law

This letter will be construed in accordance with and governed by the laws of the State of Illinois, without regard to the choice of law principles thereof.  Any suit, action or other legal proceeding arising out of or relating to this Agreement shall be brought exclusively in the Federal or state courts located in the State of Illinois.  You agree to submit to personal jurisdiction in the foregoing courts and to venue in those courts.  You further agree to waive all legal challenges and defenses to the propriety of a forum in Chicago, Illinois and to the application of Federal or Illinois law therein.

Please confirm acceptance of the terms set out in this letter by signing below and returning a copy of the signed letter to me.

Sincerely,

/s/ Gregory J. Besio

Gregory J. Besio

EVP, Chief Human Resources Officer

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Employee’s Acknowledgement:

By signing below, I acknowledge receipt of this letter; I accept the terms and conditions contained herein; and I consent to this international assignment.  For the avoidance of doubt, nothing in this letter is intended to diminish my rights under my current employment arrangement with the Company (including, if applicable, my employment agreement with the Company), or any plan or equity-based award agreement, and I will continue to be entitled to the rights and benefits under any such arrangement during this international assignment.  Notwithstanding the foregoing, I acknowledge and agree that my consent herein to the international assignment, and my acceptance of this particular international assignment to London and my repatriation thereafter, shall not give rise to any right to terminate for good reason (as defined in the employment agreement, if applicable) now or hereafter.

I further acknowledge that I have read and agree to be bound by the Company’s tax equalization policy (as set forth on Appendix A).  With regard to that policy, I specifically agree acknowledge and agree that: if I owe any monies to the Company I will make payment of such monies to the Company within 60 days of receiving notification of the amount due; and authorize the Company to deduct (or reduce from my earnings) any amounts owed under this policy from my paycheck where permitted by law.

/s/ Christa Davies	January 12, 2012
Christa Davies	Date

6

Appendix A

Tax Equalization Policy

The Company will apply the following tax equalization policy to ensure that the income and social taxes you pay will be no more than that you would have paid had all of your earnings been taxable solely in the U.S.  For the avoidance of doubt, the policy does not provide for the grossing up for U.S. income and social taxes on the relocation benefits described in the letter to which this Appendix A is attached.

The Company will determine an estimate of the tax liability you would have paid in the U.S. on your earnings from the Company, known as your “hypothetical” tax liability, and will deduct this estimated hypothetical tax from your monthly earnings via the Company’s U.S. payroll.  This policy will not protect you in your capacity as a shareholder of the Company from capital gains recognized pursuant to U.S. federal income tax as a result of the merger; however, your earnings related to granting or vesting of equity-based awards during your international assignment will be covered by this policy.

Hypothetical tax is paid on salary and on any other income paid to you by the Company (e.g. bonus) or compensation recognized by you (e.g., granting or vesting of stock-based incentives). Please note, for the avoidance of doubt, the Company will deduct hypothetical tax from your income at the point the income is paid to you and not by reference to the payment date that might have applied had you not taken up the assignment.

For a comprehensive description of the hypothetical tax procedures, please see “Aon International Tax Equalization Policy”, a white paper prepared by Corporate Finance in December 2010.

Please note that you will be responsible for the cost of any tax or additional charges arising in any tax jurisdiction on any personal income or gains, spousal income or any other U.S. source income.

For the duration of your assignment and any tail period required, the Company will authorize and pay for a tax adviser to: (1) prepare your joint or individual U.S. Federal and State, and U.K. tax returns as required; and (2), reconcile the hypothetical tax deductions made from your earnings.

If the amount of your final hypothetical tax liability to the Company is greater than the amount of any estimated hypothetical tax payments deducted by the Company from your salary or other payments, then you will be required to pay the additional hypothetical tax to the Company within 60 days of the relevant tax returns being finalized.  If it is less, then the Company will reimburse any excess to you within 60 days.

Provided you meet your obligations to the Company in respect of your hypothetical tax liability and provide such information and assistance as the Company and/or its designated tax adviser shall require in order to resolve your tax affairs on a timely basis and within the filing deadlines set down by the applicable tax authorities, the Company will pay any actual tax or social security liability arising in respect of your earned income.

Should you delay providing the necessary information to the tax advisers you will be responsible for any additional fees and/or penalties that arise as a result of the delay.

Although the Company will retain and pay an external tax adviser on your behalf to prepare your tax returns and to calculate your tax equalization calculations, it remains your personal obligation to file such returns within the applicable time limits and to abide by the tax laws in both the U.S. and U.K.  The external tax adviser will provide regular information regarding your obligations and filing schedules.

7

EX-10.3

Exhibit 10.3

Steve McGill

Aon Corporation

USA

January 12, 2012

International Assignment – Chicago, Illinois (U.S.) to London, England

Dear Steve,

Your relocation to London is critical to Project Market and will help us realize the benefits of the transaction for all concerned stakeholders.  As you know, the transaction is anticipated to position the company for future growth, improve our financial flexibility, and increase our ability to invest globally in strategic initiatives and talent.

We recognize this assignment will require a significant time commitment, as well as personal adjustment and inconveniences for you and your family. However, we are committed to working with you to ensure that your international assignment is as successful and smooth as possible.

This letter sets out the terms of your assignment and the assistance we are committed to provide in connection with your relocation, consistent with the approval of, and directions provided by, the Organization and Compensation Committee of the Company’s board of directors.

1.Introduction

This assignment is subject to your acceptance of the terms and conditions outlined in this letter, which sets forth the entire agreement between you and the Company regarding your international assignment.  To the extent that anything in this letter conflicts with your current employment terms or agreement, or the Company’s Employee Handbook, this letter, once countersigned by you, will be a variation to your employment terms.  Unless otherwise specified herein, your current employment terms and conditions will remain unchanged for the duration of the international assignment.

2.Employment Status

These terms and conditions will only be in effect for the period of this assignment.  During this period you will remain an employee of Aon Service Corporation or Aon Corporation, as applicable (“the Company”).  You will be expected to conform to the general requirements of the Company’s Employee Handbook and any local rules and procedures and relevant legislation.  During the assignment, you will be seconded (loaned) to Aon Global, Limited, Aon’s parent company in London, England.

3.Assignment Duration

Your assignment will commence on a date to be mutually agreed on or before September 1, 2012.  The duration of the assignment is expected to be less than 24 months, after which you will return to the Company’s offices in Chicago, Illinois, provided that the Company may, in consultation with you, extend or shorten your assignment according to business needs and/or your personal circumstances. In the event that your assignment is extended beyond 36 months the Company reserves the right to “localize” your terms.

1

4.Immigration

Your assignment is conditional upon the Company being able to obtain and maintain the appropriate work permit, visa and/or other authorization documents for you to work and remain in London, England.  The Company will cover the cost of obtaining and maintaining the appropriate work permit/visa for you.  In addition, should you desire and consistent with current policy, the Company will also assist your spouse or partner in obtaining a work permit, visa and/or other authorization documents to work in London.

5.Changes to Compensation Arrangements

The changes to your compensation and benefits package during your international assignment, as described below, are designed to provide you with a level of income and benefits which do not disadvantage you in comparison to those you would have received in the United States. We have also taken into consideration any additional costs that you may reasonably incur as a result of living in London.  Unless otherwise noted below as being a non-taxable benefit, the following benefits will be provided to you subject to income and social taxes.

5.1.Cost of Living Allowance

You will receive an annual cost of living allowance of US$90,000.  The allowance is intended to replicate your U.S. purchasing power in London and is based on a family size of four.  The allowance will be paid semi-monthly via your U.S. payroll

5.2.Car Allowance

You will receive an annual car allowance of US$23,500 (GBP15,000) while on assignment in the U.K.  Some or all of this allowance may be non-taxable to you, depending on the extent of your usage of transportation for Company business. This allowance will be reviewed and adjusted annually to reflect local market practice.  The allowance will be paid semi-monthly via your U.S. payroll.

5.3.Household Goods Move

The Company will pay the transportation and moving cost of you and your family to London from the U.S. at the beginning of your assignment in line with the Company’s relocation policy for an international household goods move. All or a portion of the benefits described in this paragraph 5.3 may be non-taxable to you.

5.4.Relocation Allowance

You will receive a one-time relocation allowance of US$80,000 in the first month you are working in London. This allowance is intended to cover all miscellaneous expenses not covered by other provisions included in your relocation package.  All or a portion of this allowance may be non-taxable to you if used to purchase certain goods or services related to the international assignment, as evidenced by receipts.  Your independent tax advisor will provide the criteria.

5.5.Waiver/Retention Bonus

You will receive a waiver/retention bonus of US$200,000 as consideration, and in exchange, for your acknowledgement and agreement that your consent herein to the international assignment, and your acceptance of this international assignment to London and repatriation thereafter, shall not give rise to any right to terminate for good reason (as defined in your employment agreement, if applicable) now or hereafter.  This bonus will be paid in two equal lump sums: one-half in the month prior to your relocation to London; and, one-half on the 12 month anniversary of the relocation date.

5.6.Income Taxes Payable in the U.K. (Equalization Tax)

It is likely that all or a portion of your earned income during any given U.K. tax year will be subject to tax in the U.K. The Company applies a tax equalization policy (as described in

2

Appendix A) which is designed to ensure the income and social taxes you pay will be no more than what you would have paid had all of your earnings been taxable solely in the U.S. For the avoidance of doubt, the policy does not provide for the grossing up for U.S. income and social taxes on the relocation benefits described herein.

5.7.Tax Preparation Services

The Company will also provide you with enhanced tax preparation, financial planning and expatriate services for the tax years covered by the international assignment and tax years for which international earnings are taxed by U.K. tax authorities following repatriation at the conclusion of the assignment.

6.Hours of Work and Holidays

Your work schedule, work hours and observed holidays will follow the practice in London.

7.Repayment Agreement

Should you elect to resign from the Company to work with a direct competitor, during your assignment or up to 12 months after the end of your assignment, the Company reserves the right to require repayment of all expatriate allowances you received in the preceding 12 months.  You agree that the Company may set off any such amounts against any amount the Company owes you on or after termination of your employment.

Additionally, with respect to the waiver/retention bonus only, if you resign for any reason while on the international assignment or the Company terminates your employment for cause (as defined in your employment agreement), you will be obligated to repay promptly to the Company a pro-rata portion of the annual waiver/retention bonus.  The prorated portion to be repaid will be calculated according to the following formula:  (the number of months remaining before the next succeeding anniversary date of the beginning of the international assignment divided by 12) x the USD value of the annual waiver/retention bonus.

Should you depart the Company due to mutual consent, the repayment obligation in this paragraph 7 will not apply.

8.Termination of Employment

If your employment is terminated without cause while on assignment, the Company will pay reasonable transportation and moving costs for you and your family to return to the U.S.  For avoidance of doubt, in this instance the company will continue to provide tax preparation and planning services for the tax years covered by the international assignment and tax years for which international earnings are taxed by U.K. tax authorities following repatriation.

Should you be terminated for cause or voluntarily terminate your employment without mutual consent while on assignment, you will bear all relocation and other costs arising after your termination for cause or resignation date.

9.Completion of Assignment

At the end of your assignment the Company will endeavor to repatriate you into a position consistent with your then current employment agreement, if applicable, and in accordance with your capabilities, interest and career potential.  Your relocation will be managed in accordance with the provisions of the Company’s policy.

10.Repatriation Assistance

The Company will pay the transportation and moving cost for you and your family back to the U.S. at the end of your assignment in accordance with the Company’s international relocation policy.

3

11.Third Party Beneficiary

Each related entity of the Company is a third party beneficiary of this letter, and each of them has the full right and power to enforce rights, interests and obligations under this letter without limitation or other restriction.

12.No Waiver

No failure or delay by any party in exercising any right, power or remedy under this letter shall operate as a waiver thereof, nor shall any single or particular exercise of the same preclude any further exercise thereof or the exercise of any other right, power or remedy.  Without limiting the foregoing, no waiver by any party of any breach of any provision of this letter shall be deemed to be a waiver of any subsequent breach of that or any other provision of this letter.

13.Withholding and Deductions

While it is anticipated that all or most of your compensation from the Company will be subject to a hypothetical tax deduction rather than actual tax withholdings, all amounts paid pursuant to this letter shall be subject to deductions and withholding for taxes (national, local, foreign or otherwise) to the extent required by applicable law.

14.Code Section 409A

We intend that this letter and the benefits provided hereunder be interpreted and construed to comply with Section 409A of the U.S. Internal Revenue Code of 1986, as amended (“Code Section 409A”), to the extent applicable thereto. The time and form of payment of compensation, expense reimbursements and payments of in-kind benefits described herein will be made in accordance with the applicable sections of this letter, provided that with respect to termination of employment for reasons other than death, the payment at such time can be characterized as a “short-term deferral” for purposes of Code Section 409A or as otherwise exempt from the provisions of Code Section 409A, or if any portion of the payment cannot be so characterized, and you are a “specified employee” under Code Section 409A, such portion of the payment will be delayed until the earlier to occur of your death or the date that is six months and one day following your termination of employment (the “Delay Period”).  Upon the expiration of the Delay Period, all payments and benefits delayed pursuant to this section will be paid or reimbursed to you in a lump sum, and any remaining payments due under this letter will be payable at the same time and in the same form as such amounts would have been paid.  For purposes of applying the provisions of Code Section 409A, each separately identifiable amount to which you are entitled will be treated as a separate payment.

15.Governing Law

This letter will be construed in accordance with and governed by the laws of the State of Illinois, without regard to the choice of law principles thereof.  Any suit, action or other legal proceeding arising out of or relating to this Agreement shall be brought exclusively in the Federal or state courts located in the State of Illinois.  You agree to submit to personal jurisdiction in the foregoing courts and to venue in those courts.  You further agree to waive all legal challenges and defenses to the propriety of a forum in Chicago, Illinois and to the application of Federal or Illinois law therein.

Please confirm acceptance of the terms set out in this letter by signing below and returning a copy of the signed letter to me.

Sincerely,

/s/ Gregory J. Besio

Gregory J. Besio

EVP, Chief Human Resource Officer

4

Employee’s Acknowledgement:

By signing below, I acknowledge receipt of this letter; I accept the terms and conditions contained herein; and I consent to this international assignment.  For the avoidance of doubt, nothing in this letter is intended to diminish my rights under my current employment arrangement with the Company (including, if applicable, my employment agreement with the Company), or any plan or equity-based award agreement, and I will continue to be entitled to the rights and benefits under any such arrangement during this international assignment.  Notwithstanding the foregoing, I acknowledge and agree that my consent herein to the international assignment, and my acceptance of this particular international assignment to London and my repatriation thereafter, shall not give rise to any right to terminate for good reason (as defined in the employment agreement, if applicable) now or hereafter.

I further acknowledge that I have read and agree to be bound by the Company’s tax equalization policy (as set forth on Appendix A).  With regard to that policy, I specifically agree acknowledge and agree that: if I owe any monies to the Company I will make payment of such monies to the Company within 60 days of receiving notification of the amount due; and authorize the Company to deduct (or reduce from my earnings) any amounts owed under this policy from my paycheck where permitted by law.

/s/ Steve McGill	January 12, 2012
Steve McGill	Date

5

Appendix A

Tax Equalization Policy

The Company will apply the following tax equalization policy to ensure that the income and social taxes you pay will be no more than that you would have paid had all of your earnings been taxable solely in the U.S.  For the avoidance of doubt, the policy does not provide for the grossing up for U.S. income and social taxes on the relocation benefits described in the letter to which this Appendix A is attached.

The Company will determine an estimate of the tax liability you would have paid in the U.S. on your earnings from the Company, known as your “hypothetical” tax liability, and will deduct this estimated hypothetical tax from your monthly earnings via the Company’s U.S. payroll.  This policy will not protect you in your capacity as a shareholder of the Company from capital gains recognized pursuant to U.S. federal income tax as a result of the merger; however, your earnings related to granting or vesting of equity-based awards during your international assignment will be covered by this policy.

Hypothetical tax is paid on salary and on any other income paid to you by the Company (e.g. bonus) or compensation recognized by you (e.g., granting or vesting of stock-based incentives). Please note, for the avoidance of doubt, the Company will deduct hypothetical tax from your income at the point the income is paid to you and not by reference to the payment date that might have applied had you not taken up the assignment.

For a comprehensive description of the hypothetical tax procedures, please see “Aon International Tax Equalization Policy”, a white paper prepared by Corporate Finance in December 2010.

Please note that you will be responsible for the cost of any tax or additional charges arising in any tax jurisdiction on any personal income or gains, spousal income or any other U.S. source income.

For the duration of your assignment and any tail period required, the Company will authorize and pay for a tax adviser to: (1) prepare your joint or individual U.S. Federal and State, and U.K. tax returns as required; and (2), reconcile the hypothetical tax deductions made from your earnings.

If the amount of your final hypothetical tax liability to the Company is greater than the amount of any estimated hypothetical tax payments deducted by the Company from your salary or other payments, then you will be required to pay the additional hypothetical tax to the Company within 60 days of the relevant tax returns being finalized.  If it is less, then the Company will reimburse any excess to you within 60 days.

Provided you meet your obligations to the Company in respect of your hypothetical tax liability and provide such information and assistance as the Company and/or its designated tax adviser shall require in order to resolve your tax affairs on a timely basis and within the filing deadlines set down by the applicable tax authorities, the Company will pay any actual tax or social security liability arising in respect of your earned income.

Should you delay providing the necessary information to the tax advisers you will be responsible for any additional fees and/or penalties that arise as a result of the delay.

Although the Company will retain and pay an external tax adviser on your behalf to prepare your tax returns and to calculate your tax equalization calculations, it remains your personal obligation to file such returns within the applicable time limits and to abide by the tax laws in both the U.S. and U.K.  The external tax adviser will provide regular information regarding your obligations and filing schedules.

6

EX-10.4

Exhibit 10.4

Michael J. O’Connor

Aon Corporation

USA

January 12, 2012

International Assignment – Chicago, Illinois (U.S.) to London, England

Dear Mike,

Your relocation to London is critical to Project Market and will help us realize the benefits of the transaction for all concerned stakeholders.  As you know, the transaction is anticipated to position the company for future growth, improve our financial flexibility, and increase our ability to invest globally in strategic initiatives and talent.

We recognize this assignment will require a significant time commitment, as well as personal adjustment and inconveniences for you and your family. However, we are committed to working with you to ensure that your international assignment is as successful and smooth as possible.

This letter sets out the terms of your assignment and the assistance we are committed to provide in connection with your relocation, consistent with the approval of, and directions provided by, the Organization and Compensation Committee of the Company’s board of directors.

1.Introduction

This assignment is subject to your acceptance of the terms and conditions outlined in this letter, which sets forth the entire agreement between you and the Company regarding your international assignment.  To the extent that anything in this letter conflicts with your current employment terms or agreement, or the Company’s Employee Handbook, this letter, once countersigned by you, will be a variation to your employment terms.  Unless otherwise specified herein, your current employment terms and conditions will remain unchanged for the duration of the international assignment.

2.Employment Status

These terms and conditions will only be in effect for the period of this assignment.  During this period you will remain an employee of Aon Service Corporation or Aon Corporation, as applicable (“the Company”).  You will be expected to conform to the general requirements of the Company’s Employee Handbook and any local rules and procedures and relevant legislation.  During the assignment, you will be seconded (loaned) to Aon Global, Limited, Aon’s parent company in London, England.

3.Assignment Duration

Your assignment will commence on a date to be mutually agreed on or before September 1, 2012.  The duration of the assignment is expected to be less than 24 months, after which you will return to the Company’s offices in Chicago, Illinois, provided that the Company may, in consultation with you, extend or shorten your assignment according to business needs and/or your personal circumstances. In the event that your assignment is extended beyond 36 months the Company reserves the right to “localize” your terms.

1

4.Immigration

Your assignment is conditional upon the Company being able to obtain and maintain the appropriate work permit, visa and/or other authorization documents for you to work and remain in London, England.  The Company will cover the cost of obtaining and maintaining the appropriate work permit/visa for you.  In addition, should you desire and consistent with current policy, the Company will also assist your spouse or partner in obtaining a work permit, visa and/or other authorization documents to work in London.

5.Changes to Compensation Arrangements

The changes to your compensation and benefits package during your international assignment, as described below, are designed to provide you with a level of income and benefits which do not disadvantage you in comparison to those you would have received in the United States. We have also taken into consideration any additional costs that you may reasonably incur as a result of living in London.  Unless otherwise noted below as being a non-taxable benefit, the following benefits will be provided to you subject to income and social taxes.

5.1.Foreign Service Allowance

You will receive an annual foreign service allowance of US$120,000. While on assignment, your target annual incentive award will be 100% of the sum of your annual base salary, as in effect at the end of the bonus year, plus your annual foreign service allowance.  The allowance will be paid semi-monthly via your U.S. payroll.

5.2.Housing Allowance

During your assignment you will receive an annual housing allowance of US$252,000 (GBP160,800) [monthly allowance of US$21,000 (GBP13,400)].  The allowance is to be used to pay accommodation and furniture rental costs and associated utility costs (excluding telephone and internet access which are personal expenses).  This allowance will be reviewed and adjusted annually to reflect foreign exchange and local market rate variation.  The allowance will paid semi-monthly via your U.S. payroll.

The Company will not be responsible in any way for your current residence in your home location. The payment of your U.S. housing expenses will remain your responsibility.

5.3.Cost of Living Allowance

You will receive an annual cost of living allowance of US$90,000.  This allowance is intended to replicate your U.S. purchasing power in London and is based on a family size of four.  The allowance will be paid semi-monthly via your U.S. payroll

5.4.School Tuition Allowance

The Company will pay the tuition, application and registration fees for your children from kindergarten through preparatory/high school age to attend an American school, or equivalent, in London.  We estimate the annual cost per eligible child to be US$34,500 (GBP22,000). This allowance will be reviewed and adjusted annually to reflect foreign exchange and local market rate variation.  The allowance will be paid semi-monthly via your U.S. payroll.

5.5.Car Allowance

You will receive an annual car allowance of US$23,500 (GBP15,000) while on assignment in the U.K.  Some or all of this allowance may be non-taxable to you, depending on the extent of your usage of transportation for Company business. This allowance will be reviewed and adjusted annually to reflect local market practice.  The allowance will be paid semi-monthly via your U.S. payroll.

2

5.6.Home Leave Allowance

You and each family member that is relocating with you are entitled to one round-trip home leave to return to the U.S. for each complete year you are on assignment.  In addition, any immediate family members (e.g., university aged dependent children) not accompanying you on assignment are entitled to two round-trip flights to the U.K. for each complete year you are on assignment.

5.7.Household Goods Move

The Company will pay the transportation and moving cost of you and your family to London from the U.S. at the beginning of your assignment in line with the Company’s relocation policy for an international household goods move.  You and your spouse or partner may also make a pre-assignment visit to London at Company expense to locate permanent housing.  If necessary, you will be provided with corporate housing for up to 30 days after your arrival on assignment to allow time to finalize your permanent housing. All or a portion of the benefits described in this paragraph 5.7 may be non-taxable to you.

5.8.Relocation Allowance

You will receive a one-time relocation allowance of US$76,667 in the first month you are working in London. This allowance is intended to cover all miscellaneous expenses not covered by other provisions included in your relocation package.  All or a portion of this allowance may be non-taxable to you if used to purchase certain goods or services related to the international assignment, as evidenced by receipts.  Your independent tax advisor will provide the criteria.

5.9.Waiver/Retention Bonus

You will receive a waiver/retention bonus of US$419,976 as consideration, and in exchange, for your acknowledgement and agreement that your consent herein to the international assignment, and your acceptance of this international assignment to London and repatriation thereafter, shall not give rise to any right to terminate for good reason (as defined in your employment agreement, if applicable) now or hereafter.  This bonus will be paid in two equal lump sums: one-half in the month prior to your relocation to London; and, one-half on the 12 month anniversary of the relocation date.

5.10.Income Taxes Payable in the U.K. (Equalization Tax)

It is likely that all or a portion of your earned income during any given U.K. tax year will be subject to tax in the U.K. The Company applies a tax equalization policy (as described in Appendix A) which is designed to ensure the income and social taxes you pay will be no more than what you would have paid had all of your earnings been taxable solely in the U.S.  For the avoidance of doubt, the policy does not provide for the grossing up for U.S. income and social taxes on the relocation benefits described herein.

5.11.Tax Preparation Services

The Company will also provide you with enhanced tax preparation, financial planning and expatriate services for the tax years covered by the international assignment and tax years for which international earnings are taxed by U.K. tax authorities following repatriation at the conclusion of the assignment.

6.Hours of Work and Holidays

Your work schedule, work hours and observed holidays will follow the practice in London.

7.Repayment Agreement

Should you elect to resign from the Company to work with a direct competitor, during your assignment or up to 12 months after the end of your assignment, the Company reserves the right to require repayment of all expatriate allowances you received in the preceding 12

3

months.  You agree that the Company may set off any such amounts against any amount the Company owes you on or after termination of your employment.

Additionally, with respect to the waiver/retention bonus only, if you resign for any reason while on the international assignment or the Company terminates your employment for cause (as defined in your employment agreement), you will be obligated to repay promptly to the Company a pro-rata portion of the annual waiver/retention bonus.  The prorated portion to be repaid will be calculated according to the following formula:  (the number of months remaining before the next succeeding anniversary date of the beginning of the international assignment divided by 12) x the USD value of the annual waiver/retention bonus.

Should you depart the Company due to mutual consent, the repayment obligation in this paragraph 7 will not apply.

8.Termination of Employment

If your employment is terminated without cause while on assignment, the Company will pay reasonable transportation and moving costs for you and your family to return to the U.S.  For avoidance of doubt, in this instance the company will continue to provide tax preparation and planning services for the tax years covered by the international assignment and tax years for which international earnings are taxed by U.K. tax authorities following repatriation.

Should you be terminated for cause or voluntarily terminate your employment without mutual consent while on assignment, you will bear all relocation and other costs arising after your termination for cause or resignation date.

9.Completion of Assignment

At the end of your assignment the Company will endeavor to repatriate you into a position consistent with your then current employment agreement, if applicable, and in accordance with your capabilities, interest and career potential.  Your relocation will be managed in accordance with the provisions of the Company’s policy.

10.Repatriation Assistance

The Company will pay the transportation and moving cost for you and your family back to the U.S. at the end of your assignment in accordance with the Company’s international relocation policy.

11.Third Party Beneficiary

Each related entity of the Company is a third party beneficiary of this letter, and each of them has the full right and power to enforce rights, interests and obligations under this letter without limitation or other restriction.

12.No Waiver

No failure or delay by any party in exercising any right, power or remedy under this letter shall operate as a waiver thereof, nor shall any single or particular exercise of the same preclude any further exercise thereof or the exercise of any other right, power or remedy.  Without limiting the foregoing, no waiver by any party of any breach of any provision of this letter shall be deemed to be a waiver of any subsequent breach of that or any other provision of this letter.

13.Withholding and Deductions

While it is anticipated that all or most of your compensation from the Company will be subject to a hypothetical tax deduction rather than actual tax withholdings, all amounts paid pursuant to this letter shall be subject to deductions and withholding for taxes (national, local, foreign or otherwise) to the extent required by applicable law.

4

14.Code Section 409A

We intend that this letter and the benefits provided hereunder be interpreted and construed to comply with Section 409A of the U.S. Internal Revenue Code of 1986, as amended (“Code Section 409A”), to the extent applicable thereto. The time and form of payment of compensation, expense reimbursements and payments of in-kind benefits described herein will be made in accordance with the applicable sections of this letter, provided that with respect to termination of employment for reasons other than death, the payment at such time can be characterized as a “short-term deferral” for purposes of Code Section 409A or as otherwise exempt from the provisions of Code Section 409A, or if any portion of the payment cannot be so characterized, and you are a “specified employee” under Code Section 409A, such portion of the payment will be delayed until the earlier to occur of your death or the date that is six months and one day following your termination of employment (the “Delay Period”).  Upon the expiration of the Delay Period, all payments and benefits delayed pursuant to this section will be paid or reimbursed to you in a lump sum, and any remaining payments due under this letter will be payable at the same time and in the same form as such amounts would have been paid.  For purposes of applying the provisions of Code Section 409A, each separately identifiable amount to which you are entitled will be treated as a separate payment.

15.Governing Law

This letter will be construed in accordance with and governed by the laws of the State of Illinois, without regard to the choice of law principles thereof.  Any suit, action or other legal proceeding arising out of or relating to this Agreement shall be brought exclusively in the Federal or state courts located in the State of Illinois.  You agree to submit to personal jurisdiction in the foregoing courts and to venue in those courts.  You further agree to waive all legal challenges and defenses to the propriety of a forum in Chicago, Illinois and to the application of Federal or Illinois law therein.

Please confirm acceptance of the terms set out in this letter by signing below and returning a copy of the signed letter to me.

Sincerely,

/s/ Gregory J. Besio

Gregory J. Besio

EVP, Chief Human Resource Officer

5

Employee’s Acknowledgement:

By signing below, I acknowledge receipt of this letter; I accept the terms and conditions contained herein; and I consent to this international assignment.  For the avoidance of doubt, nothing in this letter is intended to diminish my rights under my current employment arrangement with the Company (including, if applicable, my employment agreement with the Company), or any plan or equity-based award agreement, and I will continue to be entitled to the rights and benefits under any such arrangement during this international assignment.  Notwithstanding the foregoing, I acknowledge and agree that my consent herein to the international assignment, and my acceptance of this particular international assignment to London and my repatriation thereafter, shall not give rise to any right to terminate for good reason (as defined in the employment agreement, if applicable) now or hereafter.

I further acknowledge that I have read and agree to be bound by the Company’s tax equalization policy (as set forth on Appendix A).  With regard to that policy, I specifically agree acknowledge and agree that: if I owe any monies to the Company I will make payment of such monies to the Company within 60 days of receiving notification of the amount due; and authorize the Company to deduct (or reduce from my earnings) any amounts owed under this policy from my paycheck where permitted by law.

/s/ Michael J. O’Connor	January 12, 2012
Michael J. O’Connor	Date

6

Appendix A

Tax Equalization Policy

The Company will apply the following tax equalization policy to ensure that the income and social taxes you pay will be no more than that you would have paid had all of your earnings been taxable solely in the U.S.  For the avoidance of doubt, the policy does not provide for the grossing up for U.S. income and social taxes on the relocation benefits described in the letter to which this Appendix A is attached.

The Company will determine an estimate of the tax liability you would have paid in the U.S. on your earnings from the Company, known as your “hypothetical” tax liability, and will deduct this estimated hypothetical tax from your monthly earnings via the Company’s U.S. payroll.  This policy will not protect you in your capacity as a shareholder of the Company from capital gains recognized pursuant to U.S. federal income tax as a result of the merger; however, your earnings related to granting or vesting of equity-based awards during your international assignment will be covered by this policy.

Hypothetical tax is paid on salary and on any other income paid to you by the Company (e.g. bonus) or compensation recognized by you (e.g., granting or vesting of stock-based incentives). Please note, for the avoidance of doubt, the Company will deduct hypothetical tax from your income at the point the income is paid to you and not by reference to the payment date that might have applied had you not taken up the assignment.

For a comprehensive description of the hypothetical tax procedures, please see “Aon International Tax Equalization Policy”, a white paper prepared by Corporate Finance in December 2010.

Please note that you will be responsible for the cost of any tax or additional charges arising in any tax jurisdiction on any personal income or gains, spousal income or any other U.S. source income.

For the duration of your assignment and any tail period required, the Company will authorize and pay for a tax adviser to: (1) prepare your joint or individual U.S. Federal and State, and U.K. tax returns as required; and (2), reconcile the hypothetical tax deductions made from your earnings.

If the amount of your final hypothetical tax liability to the Company is greater than the amount of any estimated hypothetical tax payments deducted by the Company from your salary or other payments, then you will be required to pay the additional hypothetical tax to the Company within 60 days of the relevant tax returns being finalized.  If it is less, then the Company will reimburse any excess to you within 60 days.

Provided you meet your obligations to the Company in respect of your hypothetical tax liability and provide such information and assistance as the Company and/or its designated tax adviser shall require in order to resolve your tax affairs on a timely basis and within the filing deadlines set down by the applicable tax authorities, the Company will pay any actual tax or social security liability arising in respect of your earned income.

Should you delay providing the necessary information to the tax advisers you will be responsible for any additional fees and/or penalties that arise as a result of the delay.

Although the Company will retain and pay an external tax adviser on your behalf to prepare your tax returns and to calculate your tax equalization calculations, it remains your personal obligation to file such returns within the applicable time limits and to abide by the tax laws in both the U.S. and U.K.  The external tax adviser will provide regular information regarding your obligations and filing schedules.

7

EX-99.1

Exhibit 99.1

News from Aon

Aon To Move Corporate Headquarters to London

- Drives global strategy and growth opportunities

- Chicago continues as headquarters for the Americas; gains 750 jobs

Chicago, IL — January 13, 2012 — Describing it as an important step in the firm’s global growth strategy, Aon Corporation (NYSE: AON), the world’s leading provider of risk management and HR solutions, today announced it will move its corporate headquarters to London.  The move provides greater access to emerging markets and takes better advantage of the strategic proximity to Lloyd’s and the London market as one of the key international hubs of insurance and risk brokerage.

Aon’s focus on identifying global opportunities in emerging markets will strengthen its ability to drive future growth, build innovative products, develop talent and deliver shareholder value.  Aon believes this move will also have several near- and long-term financial benefits, including increased financial flexibility and improved capital allocation.  As the proportion of Aon’s revenue from international operations continues to grow, the ability to allocate capital for investment and growth will be vital to the firm’s continued success.

As part of this move, Chicago will continue as headquarters of the Americas for Aon and will benefit from significant investment and local job growth.

Building on its base of 6,000 employees in Chicagoland, Aon will be moving 750 jobs into the Aon Center in downtown Chicago where the company recently signed a letter-of-intent for a 15-year lease.  “Chicago is the foundation of one of our most important markets, and as the headquarters of the Americas will continue to be central to the success of the firm,” said CEO Greg Case.  Aon plans to add more than 1,000 positions across its U.S. operations in 2012 based on continued growth and investment opportunities. The move will not cause job loss in either Chicago or the U.S.

Case added, “The decisions we make today will help drive our global strategy and strengthen our growth opportunities in the years to come.  The continued investment in our international operations and emerging markets is important to the growth of our firm.”

Transaction Summary

As part of its global growth strategy, Aon will change its jurisdiction of incorporation from Delaware to England.  The change in corporate domicile will occur through a transaction that will require stockholder approval, and if approved, each stockholder will be entitled to receive one Class A Ordinary Share (U.S. dollar denominated) of the newly formed English public limited company in exchange for each share of common stock of Aon the stockholder holds (the “Transaction”).  Aon UK expects to be listed on the NYSE and to report earnings and other financial statements in accordance with Securities and Exchange Commission regulations, including dollar denominated financial statements.  The Transaction is anticipated to close in the second quarter of 2012.

-more-

About Aon

Aon Corporation (NYSE: AON) is the leading global provider of risk management, insurance and reinsurance brokerage, and human resources solutions and outsourcing services.  Through its more than 61,000 colleagues worldwide, Aon unites to empower results for clients in over 120 countries via innovative and effective risk and people solutions and through industry-leading global resources and technical expertise.  Aon has been named repeatedly as the world’s best broker, best insurance intermediary, reinsurance intermediary, captives manager and best employee benefits consulting firm by multiple industry sources.  Visit http://www.aon.com for more information on Aon.

Safe Harbor Statement

This communication contains certain statements related to future results, or states our intentions, beliefs and expectations or predictions for the future which are forward-looking statements as that term is defined in the Private Securities Litigation Reform Act of 1995.  These forward-looking statements are subject to certain risks and uncertainties that could cause actual results to differ materially from either historical or anticipated results depending on a variety of factors.

Further information concerning Aon and its business, including factors that potentially could materially affect Aon’s financial results and the Transaction, is contained in Aon’s filings with the SEC.  See Aon’s Annual Report on Form 10-K and Annual Report to Stockholders for the fiscal years ended December 31, 2010, and other public filings with the SEC, including the definitive proxy statement for the Transaction when it becomes available, for a further discussion of these and other risks and uncertainties applicable to our business.  Aon does not undertake, and expressly disclaims, any duty to update any forward-looking statement whether as a result of new information, future events or changes in its expectations, except as required by law.

Additional Information

This communication does not constitute an offer to sell or the solicitation of an offer to buy our securities or the solicitation of any vote or approval. In connection with the proposed Transaction, Aon and Aon Global Limited, a subsidiary of Aon (“Aon UK”) will file with the SEC a registration statement on Form S-4 that includes a preliminary proxy statement/prospectus, and each of Aon and Aon UK will be filing documents with the SEC other relevant materials in connection with the Transaction. A definitive proxy statement/prospectus will be mailed to the stockholders of Aon once the registration statement has been declared effective by the SEC.

Investors and security holders of Aon are urged to read the proxy statement/prospectus and the other relevant materials when they become available because they will contain important information about Aon and the Transaction.  You may obtain copies of all documents filed with the SEC regarding this transaction, free of charge, at the SEC’s website (www.sec.gov), by accessing Aon’s website at www.aon.com under the heading “Investor Relations” and then under the link “SEC Filings.”

Aon, Aon UK and their directors and executive officers and certain other members of management and employees may be deemed to be participants in the solicitation of proxies in respect of the Transaction. You can find information about Aon’s directors and executive officers in its definitive proxy statement filed with the SEC on April 8, 2011.  Other information regarding the participants in the proxy solicitation and a description of their direct and indirect interests, by security holdings or otherwise, will be contained in the proxy statement/prospectus and other relevant materials to be filed with the SEC when they become available. You can obtain free copies of the documents using the above contact information.

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David Prosperi	Scott Malchow
Vice President, Global Public Relations	Vice President, Investor Relations
312.381.2485	312.381.3983
david.prosperi@aon.com	scott.malchow@aon.com