I suggest that your Certificate is wrong as this is QR206 - there is no higher Authority than HMTQ:
206. Flying Badges - wearing of.
Flying badges are divided into two categories, those in current issue, for which aircrew are qualified under the terms of paras J727 and 728 and those no longer issued, for which members of the RAF qualified under regulations in force from time to time.
These badges are:
(a) Current issued: Pilot, Weapons Systems Officer (WSO), Weapons Systems Operator (WSOp), Fighter Controller (FC), Airborne Technician (AT), The Preliminary Flying Badge (Pilot), UAS personnel only. See para 728.
(b) Previously in issue: Navigator(N), Air Electronics Officer(AE), Air Electronics Operator(AE), Air Engineer(E), Air Signaller(S), Air Loadmaster(LM), Air Observer (O), Air Bomber (B), Wireless Operator (air) (S), Wireless Operator Mechanic (air) (S), Meteorological Air Observer (M), Observer (radio) (RO), Air Gunner (AG), The Preliminary Flying Badge (Navigator), The Preliminary Flying Badge (Signaller), The Preliminary Flying Badge (Engineer), The Preliminary Flying Badge (Gunner)
No where can I see “The RAF Flying Badge”??? All I can see is “Pilot” under “Flying Badges”? So I suspect your Course Completion Certificate is wrong, just like others have been with the term “Brevet”?