I believe all the BBMF aircraft are still classed as military stock and are maintained under the management of the RAF’s Large Aircraft Project Team (wot some of us knew as the Eng Authority(EA))

I also believe that in recent years they have undergone some serious re-assessment of their airworthiness – due (I think) to Haddon-Cave and the fact that these aircraft fly over the public most of their time.

But I might be wrong – of course!