As I understand it, in the 60s and 70s, the rules for wearing flying badges/brevets were that you had to wear your current brevet; but after you were no longer appointable to flying duties you could wear any brevet you had been entitled to.
So lots of ex "O" brevet wearers were still in the RAF but no longer flying.
There was a Wing Commander Admin at Topcliffe who wore either an "O" or Pilots Wings as the mood took him.
The rules may still apply.