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                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549
 
                         Commission File number 0-19152
 
                       AUTOMATED SECURITY (HOLDINGS) PLC
                               ENGLAND AND WALES
                (Jurisdiction of incorporation of organization)
            The Clock House, The Campus, Spring Way Hemel Hempstead,
                         Hertfordshire HP2 7TL England
                         (Address of principal offices)
                                    FORM 6-K
                        REPORT OF FOREIGN PRIVATE ISSUER
                      PURSUANT TO RULE 13a-16 OR 15d-16 OF
                      THE SECURITIES EXCHANGE ACT OF 1934
 
    (Indicate by check mark whether the registrant files or will file annual
reports under cover of Form 20-F or Form 40-F.)
 
    Form 20-F /X/    Form 40-F / /
 
    (Indicate by check mark whether the registrant by furnishing the information
contained in this form is also thereby furnishing the information to the
Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of
1934.)
 
    Yes / /    No /X/
 
    (If "Yes" is marked, indicate below the file number assigned to the
registrant in connection with Rule 12g3-2(b): 82-     .)
 
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                                                                          [LOGO]
 
FOR IMMEDIATE RELEASE
 
                                  Contact: Peter Bertram
                                         Automated Security (Holdings) PLC
                                         011-441-44-260-008
                                                   -or-
                                         Brian Rafferty
                                         Taylor Rafferty Associates
                                         212-889-4350
 
ACQUISITION OF AUTOMATED SECURITY (HOLDINGS) PLC ("ASH") BY ADT LIMITED ("ADT");
SCHEME OF ARRANGEMENT EFFECTIVE
 
    London, September 4, 1996--The scheme of arrangement to effect the
acquisition of ASH by ADT was sanctioned by the Court earlier today. Therefore,
subject to the satisfaction or waiver by ADT of the outstanding conditions, the
Scheme is expected to become effective tomorrow, September 5, 1996.
 
    IN CONNECTION WITH THIS TRANSACTION AND IN THE PREPARATION OF THIS PRESS
RELEASE, CHARTERHOUSE BANK LIMITED AND SMITH BARNEY INC. ARE ACTING EXCLUSIVELY
FOR ASH. CHARTERHOUSE BANK LIMITED AND SMITH BARNEY INC. ARE NOT ACTING FOR ANY
OTHER PERSON AND WILL NOT BE RESPONSIBLE TO ANY OTHER PERSON FOR PROVIDING
PROTECTIONS AFFORDED TO CUSTOMERS OF CHARTERHOUSE BANK LIMITED OR SMITH BARNEY
INC. OR ADVISING THEM ON THIS TRANSACTION OR ON THE CONTENTS OF THIS PRESS
RELEASE. CHARTERHOUSE BANK LIMITED AND SMITH BARNEY INC. ARE REGULATED BY THE
SECURITIES AND FUTURES AUTHORITY LIMITED.

                                   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.
 
                                          Automated Security (Holdings) PLC
 
                                          By:          /s/ PETER BERTRAM
 
                                             -----------------------------------
                                              Peter Bertram
                                             Chief Financial Officer
 
Date of signing: September 4, 1996