Actually it's more like they held off an invasion. It had more to do with Hitler's invasion of Russia then it did with the fighting ablitiy of the British people.
The invasion of Russia and declaration of war on the US, by NAZI Germany where two of the biggest military blunders of all time and proably actually lost him the war in Europe. Course I heard he was high as a kite when he made those calls.
Of course he was, but then you take too much away from the RAF.
Well no doubt the RAF where good at what they did, but they really were fighting a losing battle. With the development of the V1 and V2 Rockets and the Jet engines just around the bend for the Nazis, it was only a matter of time before Britain fell. If Hitler had let Russia be and landed troops on the isle instead, we would have fought tooth and nail for parts of Whales instead of Normandy in France.
Lucky for the Brits a stroke of good luck came their way and the island was saved, but I wouldn't say they fought off the invasion, more prolonged the inevitable long enough for someone else to become involved. Churchill himself knew that Britain was doomed unless America became involved in the war and was constantly trying to talk Roosevelt into it, but the strict isolationist feelings of the people kept that from happening. Course that all changed Dec 7 1941.
Then came the other great blunder. Japan had attacked America. We declared war on them and only them at first. This would have kept America out of the war in Europe for the most part (Although I'm sure we would have become involved after the conflict with Japan.) but Hitler declared war on us, and thus gave us an excuse to move into Europe first, basically signing his own death warrant.