Retirement benefits (Tables)

12 Months Ended

Dec. 31, 2020


	Defined benefit obligation									Fair value of plan assets									Net defined benefit liability/(asset)
	2020 $m			2019 $m			2018 $m			2020 $m			2019 $m			2018 $m			2020 $m			2019 $m			2018 $m
At 1 January		96			91			250			—			—			(152	)		96			91			98

Recognised in profit or loss

Interest expense/(income)		3			3			6			—			—			(2	)		3			3			4

Exceptional item: settlement loss		—			—			14			—			—			1			—			—			15

		3			3			20			—			—			(1	)		3			3			19

Recognised in other comprehensive income

Actuarial loss/(gain) arising from changes in:
Demographic assumptions		(3	)		(1	)		—			—			—			—			(3	)		(1	)		—

Financial assumptions		10			9			(14	)		—			—			—			10			9			(14	)

Experience adjustments		1			(1	)		(3	)		—			—			—			1			(1	)		(3	)

Return on plan assets		—			—			—			—			—			8			—			—			8

Re-measurement loss/(gain)		8			7			(17	)		—			—			8			8			7			(9	)

Exchange adjustments		2			1			(1	)		—			—			—			2			1			(1	)

		10			8			(18	)		—			—			8			10			8			(10	)

Other

Group contributions		—			—			—			(6	)		(6	)		(16	)		(6	)		(6	)		(16	)

Benefits paid		(6	)		(6	)		(11	)		6			6			11			—			—			—

Settlement payments		—			—			(150	)		—			—			150			—			—			—

		(6	)		(6	)		(161	)		—			—			145			(6	)		(6	)		(16	)

At 31 December		103			96			91			—			—			—			103			96			91

Comprising:

UK unfunded plan		31			26			24			—			—			—			31			26			24

US unfunded plans		50			48			45			—			—			—			50			48			45

US unfunded post-retirement plans		22			22			22			—			—			—			22			22			22

		103			96			91			—			—			—			103			96			91


	Defined benefit obligation									Fair value of plan assets									Net defined benefit liability/(asset)
	2020 $m			2019 $m			2018 $m			2020 $m			2019 $m			2018 $m			2020 $m			2019 $m			2018 $m
Movement in asset restriction

At 1 January		—			—			—			—			—			3			—			—			3

Recognised in other comprehensive income		—			—			—			—			—			(3	)		—			—			(3	)

At 31 December		—			—			—			—			—			—			—			—			—

The principal financial assumptions used by the actuaries to determine the defined benefit obligations are:


	2020 %		2019 %		2018 %
UK plan only:

Pension increases		3.0		2.7		3.2

Inflation rate		3.0		2.7		3.2

Discount rate:

UK plan		1.4		2.1		3.0

US plans		1.9		2.9		3.9

US post-retirement plan		2.0		2.9		4.0

US healthcare cost trend rate assumed for the next year:

Pre-65 (ultimate rate reached in 2029)		6.4		6.7		7.1

Post-65 (ultimate rate reached in 2029)		6.8		7.1		7.6

Ultimate rate that the cost rate trends to		4.5		4.5		4.5

The assumptions used for life expectancy at retirement age are as follows:

a	Relates to assumptions based on longevity (in years) following retirement at the end of the reporting period.

b	Relates to assumptions based on longevity (in years) relating to an employee retiring in 2040.

The sensitivity analysis below relates to the benefit obligation and is based on extrapolating reasonable changes in these assumptions, using

year-end

conditions and assuming no interdependency between the assumptions:


		Increase/(decrease) in liabilities $m
Discount rate	0.25% decrease		3.2

	0.25% increase		(3.2	)

Inflation rate	0.25% decrease		(1.4	)

	0.25% increase		1.4

Mortality rate	One-year increase		5.7

Healthcare costs trend rate	1% decrease		(1.6	)

	1% increase		1.7