What is the reason for the QCS NCOs having those massive gopping chevrons on their greatcoats? Why not the rest of the RAF?
Because it’s the QCS and they have several bits of kit that are regiment only.
RAF DPC was formally sorting this out for the broader Air Force. So the intention was to stop simply slapping No1 pattern ranks onto them, and go upscaled super-size.
In fairness, I suspect RAF bandsmen also already have these bigger rank-badges eg when Central Band are in performance practice/rehearsal ‘dress-down order’, ie greatcoats without gold-wire badges (viz fitted with large chevs&props embroidered in ‘wedgewode’/minerva blue on midnight blue felt & suchlike)
This was evident from a redacted FOI memo published as an open-source reference available online.
Related to this was an intention to improve the design of the issued embroidered WOs rank-badge (whether as worn on the cuff in No1s & greatcoats, or as slides on shoulders & chests)*
IIRC there was a concern that private purchase versions of such badges were too good in comparison with the issue item (this, more than actual variations between them)
My guess on this is it might be related in some way to the small (but significant) quantities of ‘Command’ WO posts, and also perhaps MACr badging. It might also be in order to try & maintain inter-service consistency for sizes of rank emblems in common contexts.
(* ps I did wonder whether that maybe explained the lengthy delay into Apr 2020 for the WO(RAFAC) Royal Arms rank-badge changeover…?)
It is not only the QCS who have different types of chevrons. In the army the Brigade of Guards NCOs wear the larger old battle dress chevrons on No2 Dress while the rest of the army use a smaller variation in No2 Dress.
People are used to strange uniform differences in the Army. It’s normal. The QCS are the odd ones out.