Churchill was an incomparable war-time leader, probably the best in history. He showed an indomitable spirit and a way of encouraging people through the darkest hours that no one has ever equalled and a unique way of expressing pugnacity and belligerence without sounding brutal or bloodthirsty. Many men of my father's generation could quote from memory from many of his war-time speeches. All agreed that he was a great inspiration.
Churchill was, however, far from ideal as a peace-time leader, and may not have been suited to lead a country under enemy occupation either. His spirit of resistance is appealing to the boy-scout nature of every man, but the British people may have been a lot more practical than Winston in some respects. Specifically, the ruthless nature of Nazi reprisal against helpless civilians doesn't seem to factor into any of Winston's equations, but I'm pretty sure that the British people themselves would have been a lot more concerned with such factors. One or two Oradour-type reprisals could easily have given the BRO some brakes for their enthusiasm.
I think a lot depends on the severity of the occupation. In France, for example, while there were always individual resisters and small cells from the start of the occupation, the resistance didn't really take off until the Vichy regime instituted the Service du Travail Obligatoire ("STO") whereby French youth would be drafted for labour service inside Germany. This sent thousands of French youth fleeing into the ranks of the Resistance fighters, whereas the pre-STO resistance had been more or less limited to a relatively few hard-core anti-fascist ideologues.
