Pretty specialist work. Sheer wild guess, whoever does Sally B. Or Marshall’s. This assumes out-sourcing. No doubt the RAF will find somewhere to do it in-house?
I remember being led around the hangars as a sprog when G-AMSV had it’s wings off for a check. I later lost two virgin cherries that day, 1. getting to fly and 2. first case of airsickness 😀
Bet plenty of local SEP GA traffic transit overhead Bed’uff though. To me, it really sounds like over cautious jobsworth advice from a rep at our dear CAA.
edit: if Spits are on CAA Permits, I think this may have been why?