Elliott Bros site at Borehamwood had a Computing Division as early as 1949 and this continued until the GEC takeover in 1968. When in 1968 ICL was formally registered as a company to make general purpose computers the remaining process control and military computer activity within English Electric and Elliott-Automation were established in a new company called Marconi-Elliott Computer Systems Ltd (MECS). The new company included the work at Borehamwood , Kidsgrove,and Chelmsford but not Rochester. Almost immediately after GEC took over English Electric the company name was changed to GEC Computers Ltd in 1971. The main site was at Borehamwood where the company was eventually absorbed by GEC Telecommunications at Coventry simply becoming Telecommunications in 1999 and finally disappeared with the collapse of Marconi plc 2006.
See ‘Moving Targets’ by Simon Lavington