This revisionist believes it. Why Britain and France did not put up much of a fight is no mystery. Appeasement continued after September 1939. Montagu Norman, the governor of the Bank of England, viewed Germany as a bulwark against the greater threat of Bolshevism. Other parts of the British elite viewed the war as benefitting "the Jews". Uppler class twit anti-semitism was less genteel and more brazen than now. And it shaped the world views and policy choices of people like Anthony Eden: https://medium.com/lessons-from-history/wwii-mythbusting-tour-british-exceptionalism-4a82d62def64

Large parts of the French elite were more afraid of Popular Front socialism than the Nazis. Renoir's film, The Rule of the Game, shows the rot at the pinnacle of French society.

What's the title of your book?