Can Britain be trusted?

Julian Assange is being pressured to leave the Equadorian Embassy after Embassy Officials state that months of quite diplomacy have resulted in Britain giving assurances that Mr Assange will not be extradited to the US unless the US removes the option of the death penalty.
I believe the US will acquiesce to this request and Mr Assange will be extradited to the US and face the rest of his life in prison.