I came across this thread purely by accident when googling other RAF matters and notice that most of the training posts are made by pilots who usually started training around 1941/42.I volunteered for aircrew in January of 1943 and was subsequently called in front of the selection board about four months later.
This board consisted of a WW1 Group Captain whose main interest was in knowing whether " you played rugger old boy" but having been to an elementary school, I couldn't satisfy him on that score, and if memory serves me, a Squadron Leader who did not have much to say. Anyhow I was accepted as PNB and then had to undertake the infamous aircrew medical including the mercury blowing and holding your breath for what seemed an interminable time.
Having survived these hazards I was then sworn in, given the RAFVR lapel badge and placed on deferred service. Thus began the tortuous route to gaining a flying brevet.