Maybe forming an alliance with the biggest mass-murderer in History before WW II began was repugnant to them.
If Chamberlin was not the British idol of the day, and the English had shown some balls in the Rhineland take over, WW2 might not have happened.
Most Britons had contempt for Neville Chamberlain, it was only the NAZI sympathisers like Lord Halifax, Mosely and, of course, Edward the VIII, who encouraged him.
Yes, WW II need not have happened. Hitler should have been stepped on when he first violated the treaty of Versailles. But that wasn't an excuse for the USSR to join up with Hitler and occupy Poland. Britain declared war on Germany because of the invasion of Poland, which your lot aided Germany with.
P.S. I was amused by the behaviour of your Russian youth after you were beaten by Japan the other week. It looks like the wonderful discipline and nationalism (military training for school children and conscription) you have in Russia and which you often boast about, have some unfortunate side effects.