Don't confuse the empire with the commonwealth. Calais and the Falklands were both seized by us hundreds of years ago. Is there a need to hang on to the latter, if there is no strategic or financial/resource based reason? If we still had Calais the asylum argument would have strange results. Sell or sell and leaseback the Falklands.Nonsense.
The Commonwealth is still intact as far as i know and the French can have Calais for all the use it is to us.
What difference did it make when we gave it back?
Maybe it is time for Elgin's marbles to be returned - would it make any difference to the BM?