I remember reading the memoirs of a Female ATA pilot during WWII (Don't recall her name at the moment).
She mentioned that the crewing was somewhat haphazard and depended on the experience of the Pilot, the route flown and availability of other crews. If there as an FE available then you could have one - if not, then you couldn't. She made mention of the fact that when flying Lancasters she was given an "assistant" because her very small stature meant that she was unable to reach a particular piece of equipment or control unaided (Don't remember what it was) This assistant was often a ground-crew or an air cadet and their sole function was to "push the doo-dah when I told them to".
On the subject of boy-scouts and girl guides. Extensive use was made of girl guides as office messengers for the intelligence and security services in London during the first world war (their offices were scattered across London) and also, I believe, during WWII. Apparently girls were chosen rather than boys as they were less inclined to mess around and gossip.
OH