Re Chugalug2 "BTW, I seem to remember in the film Lawrence Olivier (as Dowding) saying that he had lost 400 aircraft in and over France, whereas this programme spoke of 900 I think. Were the other 500 not from Fighter Command?"
This explains for me why he put his foot down at that war office meeting with Churchill and insisted that the remaining squadrons were to be kept back for the coming defence of Britain. And Churchill backed down, despite his promise to the desperately pleading French.