Last year, when a mob of Iranian students stormed the UK embassy in Tehran, the British government expressed its outrage. Diplomatic premises were inviolable, they said, and Syria had to be punished for failing to protect them.
You don't have to approve of Assange or his weak case for asylum to see this as deeply hypocritical. The UK can not have it both ways. Either diplomatic premises are inviolable and sovereign, or they are not. And if the UK chooses the latter, then it won't have a leg to stand on when people do the same to their embassies in future.