JF:-
"..do you mind if I don't join the RAF?... joined the Northumbria UAS, had two terrific years flying out of Leeming"
motn:-
The UAS is deciding that they don't need to spend money on someone who already wants in.
Deciding instead to spend money on someone who already doesn't want in? I'm as confused as the OP, and it seems to me he has asked a very pertinent question. I admit though to being a BOF who has had to learn the hard way to regularly switch accounts, policies, and contracts every year to get the best deals. The best way to join a UAS would it seems be to study an "ology" and have no interest in joining the RAF at all...