Surely the actual reason is that the average pongo officer is such a dimwitted inbred that he requires a competent NCO to complete any task more demanding than sitting on a horse? Flying an aircraft would be beyond the skill set of most of them, so those more intelligent are chosen....
'Somewhere outside Saffron Walden there's an uncle who is seven feet tall with no chin and an Adam's apple that makes him look as if he's constantly trying to swallow a ballcock.'
Yup, pretty well sums up the pedigree of the average Woopert of the Wedgiment.....
(And no, of course I'm not being serious! Not
that serious, I should add.)