Papers relating to the 3SL Estriel Mainframe Computer

International Computers Ltd (ICL) was a British company formed in 1968 as a part of the Industrial Expansion Act of the Wilson Labour Government. ICL was an initiative of Tony Benn, the Minister of Technology, to create a British computer industry that could compete with major world manufacturers like IBM. English Electric Leo Marconi (EELM) was merged with the computer interests of Elliott Automation which was then taken over by International Computers and Tabulators (ICT) to form International Computers Limited (ICL). Plessey Co and English Electric each owned 18% of the equity of ICL, with 53.5% in the hands of former shareholders of ICT and the remaining 10.5% held by the government. ICL represented the last step in a series of mergers that had taken place in the industry since the late 1950s.

ICL tended to rely on large contracts from the UK public sector. Significant customers included Post Office Ltd., the Inland Revenue, the Department for Work and Pensions, and the Ministry of Defence.

The company had various buildings at Bracknell (its main one being at Lovelace Road in the town); it also had numerous locations throughout the UK and worldwide. Manufacturing took place in Letchworth (Hertfordshire), Manchester and the Midlands (including Kidsgrove). It is thought that there were over 100 ICL locations in the UK alone with many more overseas.

Fujitsu's involvement with ICL steadily increased; in 1990 Fujitsu acquired 80% of ICL plc from STC. Following the acquisition of Nokia Data in 1991, personal computers and servers were marketed under the ICL brand. Eventually in 2002, Fujitsu acquired full ownership of ICL and subsequently fully integrated it, dropping the ICL brand.