Even in May 1940 Churchill wasn't popular with all MPs even Conservatives, Halifax still had supporters wanting to do a deal. Hitler believed he could avoid war with UK even if he invaded everywhere else, in part because people like Halifax were making noises that they would do a deal.Chamberlain's policy was clearly wrong on Sept 3, 1939. You think only on the invasion of France the Commons began to wonder? I do not share your view that Churchill's ascendency was guaranteed no matter the date.