Here is Theresa May, current UK PM, denying extradition of Gary McKinnon, after years of hearings, wanted for one of the largest hacks of US military networks of all time:

http://www.cnn.com/2012/10/16/world/europe/uk-us-mckinnon-ex...

The UK has a history of both courts and the Home Office denying extraditions. Theresa May is a "law and order" authoritarian to boot, but even she is not prepared to fall over herself to satisfy US extradition requests.