They died so completely, Googling "ICL" now has higher hits such as Imperial College London.
Video 1.
Why the UK's IBM Failed by Asianometry (2022)
Source. Main lesson perhaps: don't put national money to fight already established markets. You have to fight for what is coming up next. E.g. that is part of the reason for TSMC's success.

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International Computers Limited (ICL) was a British computer hardware and software company that was active primarily from the 1960s through the 1990s. Founded in 1968, ICL became one of the leading providers of mainframe computers and computing solutions in the UK and Europe. The company specialized in developing and manufacturing a range of computing systems, including mainframe computers, peripheral devices, and software solutions for various industries.