Some mid range UK developer posts pay that across the UK, but there are plenty out there that quickly pay more. London should be paying at least £6k more than that just for cost of living. London is where developers go to earn the "kick" to their salary that they can then move to the sticks on.

More important is that the pay progression is like, given the difficulty in firing people in the UK compared to the US you often find pay ramps up quickly.