As usual, Pobjoy has hit the nail squarely on the head. Here's an interesting fact, many years ago the ATC sold off its T-61s and replaced them with G109s. Most of those T-61s are still airworthy (I was flying one only last week) yet the ATC's 109s aren't. Perhaps the RAF should let the BGA and LAA look after its maintenance requirements, as all the evidence would indicate that the BGA and LAA do a better job (although to be honest the RAF have set that particular bar pretty low).