Working for a company that also has offices in UK and with team mates in London, the problem is that UK is expensive versus countries relatively close (Eastern Europe) and London is very expensive versus Warsaw, for example, so the demand is not high because companies moved a lot of business out of UK and Western Europe due to cost. In a global world where India and China are cheaper and business can move where they are treated best (taxes and cost of labor), UK is in a very bad spot. Warsaw, Budapest, Bucharest, Ljubljana are close enough and cheap enough to be preferred by companies instead of London.