Pobjoy is right. The ATC was never seen as a source of pilots for the RAF. The main thrust was the character development of the youngsters who joined. The teaching of flying and then going solo were very good at doing this but was almost incidental. I was in several gliding clubs over the years and I seldom met anyone who had been in the ATC except as a volunteer instructor. Gliding was and still is an expensive activity well beyond the means of most young people. I reckon anyone who can ride a bicycle can be taught to fly, and solo in a simple machine like a glider.