Right now there are about 20 (at best) permanent Sitecore developers in London and they are all happy in their jobs!
So your chances as a business to hire a ready and experienced Sitecore developer in this market are slim to non-existent, when there are tens of other companies like you looking to hire the best of the best at any moment in time.
Especially in the new year with numerous projects being approved and mobilized!
Our problem is that we tend to look at things as they are right now in this moment. Frozen, and not as what they are becoming.
It takes a little change of paradigm to unlock endless opportunities and possibilities.
So if you are looking to hire Sitecore developers, stop wasting your time with recruiters who are promising you the world, and join the real world.
You have two options: Either bringing in a contractor if you have urgent project needs or draw out a talent strategy for how you’ll build a solid in house team which CAN learn Sitecore.
I personally learned Sitecore development in two weeks, I can’t see why any other developer with some interest can’t do that.