Are there any micro-controllers produced by companies based in the UK?
I don't know of any Micro-controller manufacturer specifically in the UK, but under the broader umbrella of integrated circuit manufacturers, there are a small handfull. 'Silicon-fen' in Scotland (think the scottish version of silicon valley) or the Cambridge and Bristol areas are where most of them are based. 

I'm personally aware of e2v in based in Essex, who manufacture high reliability semiconductors/electronics for space and defense applications.