A Few Thoughts
Should the RAF have its own AAIB type people? No. We are not big enough for the individuals to gain the required breadth of experience maintain currency. Furthermore, unless it was a branch in its own right, the rotation on 3-year tours would exacerbate the problem. The Navy try, and do a reasonable job regarding "normal" helicopter incidents, but struggle with more complex investigations. The real senior investigators from the real AAIB are ridiculously highly qualified and have many years' experience of numerous crashes. We would be far better served by forging closer links with the AAIB and negotiating a formal arrangement for support for OOA accidents (we don't have one!).
Would ESF stop a fuel leak? No. If it only allowed "seepage", it could interfere with the fuel flow from the main tanks into the collector tanks for the fuel system. ESF does what it says on the tin - it suppresses explosions. There are self-sealing bladders that can be used in tanks but even these will not stop leaks caused by anything above a medium-calibre round. Unfortunately, the structure in the outer-wing tanks prevents the use of the bladder system.
Was there an explosion? Apart from the mine, I don't think so. We've all seen the pictures of the aircraft on fire and the fire clearly seems to be outside the wing, with no obvious damage to the wing structure from any kind of internal explosion.
Do I think there's any hint of the widely rumoured cover-up? No. In fact, I'm surprised how little has been redacted.
N Joe