The mandatory church-dodging wheeze was also tried at RAFC when I was there on 99 Entry.
A bunch of ex-Apprentices thought they could get out of things by declaring themselves to be atheists. However, the staff (even Les Rodda!) were wise to such ploys and told them they'd have to stand at ease outside the church instead. So they had another idea....
One morning they all asked to see the left-footer god-botherer, on the grounds that, after much thought, they'd come to the conclusion that Roman Catholicism was the best chance there was to rescue their heathen spirits. The RC sky-pilot was astonished and was almost on the point of ringing the Pope, or similar, to spread the good news.... But even he began to smell a rat....
Of course the reason was simple. The CofE contingent fell in at 1030 on the JMPG and were inspected, then marched off to church in squadrons. If we were lucky, we might be free by about 1230...
The Church of Jocks group met in the JM entrance at 1000 and marched off together to the CSFC church for their short service.
Whereas the RC chaps simply turned up at their church at 0930 and were done and dusted PDQ.... No inspection, no marching and a couple of hours of extra freedom.
This didn't escape the attention of the RC padre though. He told the would-be converts that instruction in Roman Catholicism would involve many hours of study and prayer - so were they really sure they were prepared to submit themselves to such hard work, given all the other pressures of Flight Cadet training.....
Needless to say, there were a few more CofE cadets marching to church the following week!