1987 Hawley Group, which already had some security operations, acquired ADT Inc of USA, the world's largest burglar and fire alarm services group[1]
1988 Hawley took control of Cope Allman and Co; Hawley changed its name to ADT[2]
1988 Sold the cleaning companies, other than hospital cleaning, to BET Initial[3]
1989 ADT focused on electronic security systems and car auctions by disposing of its property maintenance and services activities[4]
1996 Absorbed the Thorn Security business soon after EMI had been demerged from Thorn EMI, and all but a handful of the famous red 'THORN' bellboxes were replaced. However, the Fire products may still be found in many premises and until recently spares and complete systems of Thorn heritage continued to be manufactured by ADT.