What choice did they have?
In the face of the extraordinary weight of evidence that the aircraft was not airworthy and MoD had not complied with its own airworthiness regs (a depressingly familiar statement these last few years), I’d say the only choice they had was to accept the conclusion that the cause could not be positively determined and add a rider that the staffs who condoned this systemic breach of regs should be brought to book. It’s not as if they are unknown. Or were the reviewing officers not told of the problems both the RAF and Boscombe (PE) were having with their respective fleets?
As for the supposed serviceability of the aircraft, that is pure speculation especially given the evidence of trend failures previously posted by JB. Were these trends investigated? Or was the 1991 savings measure to curtail such investigations, thus compromising airworthiness, a factor? I can only speak from personal experience, but recall we were instructed to cancel all such tasks on the Design Authorities. I know the reaction of “my” contractors – “You’re ###### mad. The airworthiness system will never recover”.
And then 2 years later Safety Cases became compulsory. But if you’ve allowed a 2-3 year gap in the audit trail, and will not fund retrospective corrective action, then any Safety Case for legacy equipment is by definition flawed as you are forced to make the sweeping, and completely unverifiable, statement that the aircraft/equipment is deemed safe at the effective date of the legislation.
How much of this was discussed at the various inquiries?