Fair call, John, and I fully accept the 'under training' aspect. But I understood one's commission was 'confirmed' on completion of training, rather than 'awarded'. Thus I was [according to my letter] 'granted' a commission wef 17 Sep 63, but that it was [if you will] probationary until 'confirmed' on completion of some pre-determined stage of training. But wasn't there also something about age too? That you couldn't be a Subbie until you were 21? Or is that an old bloke's dithering?
In respect of the a/plt off, I agree it is a different fish. I was commissioned into the RAF on Graduation Day, after completing OCTU but before starting professional training. The 'acting' bit would only be deleted on successful completion of professional training. In that context, as a wg cdr I used to sit on Reselection Boards for officers who had failed their professional training. It was made quite clear that they were already commissioned, and thus had the required officer qualities, and they could not easily be cast aside ... a different role had to be found for them somewhere.