Wibbs Je suis un Rock star
I have rellies that joined the Allied forces at that time(not just the British), while others stayed at home and joined our forces. The reasonings they all gave were twofold; 1) for a couple it was pure economics in the pre war world, with few enough career options at home and 2) they were all convinced Hitler if not stopped would come here(and had planned to at some stage "Plan Grun", though interestingly at that stage Hitler would have only come at the request of the Irish gov, then again he was fond of such "requests" masking true intentions). One great uncle of mine had visited Hitlers Germany before the war. Quite a percentage of people thought it was a brave new world and an impressive state at the time. He didn't. He was very very worried about what he saw. When it kicked off and the Americans joined the war(he didn't want to "take the kings shilling" though was tempted), he joined the Yanks and requested he be deployed in the European theatre rather than the Pacific because of it.
Funny enough even coming from that background I would be very much on the fence of men with regard to those who've sworn allegiance to their country's military, who then go AWOL and join another. Doesn't quite square with me. If they had wanted to join allied forces for whatever reason, then why sign up to the IDF? Certainly those rellies of mine who made a point of staying here and joining up made a sharp distinction between those people and those that went overseas without deserting.