That's a nice map. I had no idea there were so many Bitcoin/Blockchain related companies in the UK.
The UK is a great place to set up Bitcoin companies, because it's ridiculously easy to register companies in the UK - it takes like 10 minutes and costs £12, which is why all the Ponzi schemes advertise being UK registered. I think that Blockchain.info's actual offices are in Luxembourg, so it's interesting that they're from the UK (or at least are registered there).
Plus, the Government is fairly neutral on Bitcoin like the US, except you can trust them a bit more not to be secretly trying to destroy you