AP 1358 Ch 7:
"Note. With effect 1 Apr 03 the range of 5 aircrew brevets for rear crew personnel were replaced by the single rear crew brevet (see below).
Those aircrew who were already qualified to wear old style individual brevets can opt to wear the new brevet or retain the old style but there will be no further provisioning of the current brevet."
So there you have it. There is no compulsion to change to a:
"The monogram ‘RAF’ in drab silk surrounded by a laurel leaf of brown silk, surmounted by a crown with an outspread drab silk wing 2˝" (6.35 cm) long – on dark blue melton cloth. Introduced 1 Apr 03 to replace
Navigator, Air Electronics Officer/Operator, Air Engineer and Air Loadmaster."
Now why should
Fighter Controller (FC) wear a badge to show that the are not qualified rear crew? Not all qualified "RAF/" rear crew can navigate, load, engineer, or operate so why is there a need to identify peope who can't rear crew?