Heathrow Harry,
Sorry ! (who could forget their gallant, doomed fight on two fronts), and the part their pilots played in the Battle of Britain, and the Free Polish Army and Navy who managed to get to Britain.
But I was thinking of Allies "still standing", as it were. In the same way as the Poles, we had Belgian, Dutch, Danish, Norwegian, Greek (have I left anyone out ?) Allies.
Just about all the crowned heads left in Europe were bunkered down in London. We were saluting all manner of strange Officers. There was an apocryphal tale that, later in the war, a pair of RAF Intelligence Officers dressed up as Luftwaffe Leutnants and went marching round the West End, collecting salutes, for quite a while until someone said: "Half a mo !" and called a Constable.