If they wanted to move back in, could they just jet back into Britain?
They are not British citizens, if they are asylum seekers they have first got to apply, and if they creep in, in the back of a lorry, at least they know where they live and therefore can throw them out again.
Unfortunately or not, there are a lot of people living here (or passing through) who are not British citizens, but who are denizens - have no citizenship but in the past contribute towards the country's economy and are free to come and go as they please (as I believe was Mohammed el Fayed when he owned Harrods). I guess it's been taken off the market a) because they think they might find refuge here if they still have right of entry or b) they think it might become a target for extremists if people find out whose house it is.
Money laundering going on right under our noses and we are doing nothing about it. I suppose once all the British are out of Libya we just might clamp down on it!