I'm not sure I understand what is going on with the Foreign Office and the Ecuadorian Embassy at the moment.
Apparently after PC Yvonne Fletcher was killed outside the Libyan Embassy a law was introduced to allow the reversal of status for foreign embassies, but surely that is an oxymoron.
Either we have an agreement with others for diplomats to exists and operate or we do not. This looks a bit like "we all do the same as each other except for us" which would have serious consequences abroad for our diplomats!
I presume that the law was introduced to deal with situations that could be classed as "embassies being used for terrorism", however, I do not believe that having Julian Assange as a guest in an embassy classes as an act of terrorism...