And yet I regularly get recruiter emails looking for "rockstar" developers who'll work startup hours... for £25k (~$38k). Thanks, but no thanks.
You hit the nail in the head here. From what I saw while living in London, Singapore and now in Germany is that the problem is not with the talent, but with the right compesation. There are so many hackers out there, but "rockstars" or "ninjas" for 25K GBP is an insult.
Fortunately, the government is doing its best to help UK businesses by shutting down the Tier 1 (post-study work) visa, making it almost impossible for young non-EU graduates to live, work and settle in the UK.
It seems that, unlike UK, Germany does make right moves in this direction, lowering the salary threshold for what is called "highly skilled professional", which allows people to get work permit easier and to bring their families with them with less problems.