The UK used to have DERA, preceded by the DRA which itself was a merger of other agencies. DERA was part privatized into Qinetiq. Not quite a DARPA or CSIRO equivalent because very much more defence focused, but doing the work more with employees, though with strong relationships with certain universities.

The problem the UK has is it spent so long pretending to be far less sophisticated than it was that now it has become so, to the point their security at air bases is ridiculous https://www.bbc.com/news/articles/cx24nppdx0lo . That is the level of competence that remains in that part of their industry, and consider that in tech you basically go into videogames, finance, or defence. (Or ARM, but there are only so many people there).