All aircrew (with the obvious exception of pilot) now wear the Generic RAF Brevet as far as the official word is. You can however wear trade specific brevets on your mess dress. This I was told as I left Cranwell.
Also I was told that WSO's going onto some of the tanker aircraft can still wear the 'N' brevet on there flying suit etc. as there aren't any Weapons Systems on board. But the person telling me may have been mistaken.
Hope this helps.
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