Is that all? In London? Nevermind, below poster stated supply/demand lowers the cost of PHP developers.
As others have said - the big bucks here are in contracting, but personally I'm not up for that level of risk yet. In career terms I see the later-game positions as those in management or those in consulting.
It's just programming in general in UK, isn't that highly paid.
Why is that? Lack of demand/anaemic tech industry, lack of respect for developers, or too many developers?
Think it's partly because there are very few specific dev shops, and most of the roles are in-house where development is a support activity rather than the meat.