ToD:-
What's wrong with, for example, the C-17? Voyager? Herc?
I've no idea, which of course is irrelevant. You need to ask your question of the MAA, the same Authority that presided over the Safety Case of the MB Mk 10 seat that killed Flt Lt Cunningham. Turned out there wasn't one, but they didn't know. What makes you think they know the answer to your question?
I'm sorry, I realise my post sounds truculent. It isn't meant to be. It merely illustrates the systemic dysfunction of UK Military Airworthiness. This explains it better than I can, though it gets longer as more is added :-
https://sites.google.com/site/militaryairworthiness/