The point I am trying to make is simply that the CAA (and to a lesser extent the RAF) are not objective or independent. In so far as the CAA has a general regulatory role, it has in my view a meaningful conflict of interest.
Were its investigations to unearth a body of credible evidence in support of CI, the obvious and immediate question becomes why had they not carried out these investigations before, leading to questions as to whether they were properly and proactively discharging their duties. It is a short journey from there to the question of whether the accident could have been avoided if the CAA had discharged its responsibilities diligently. Given that the evidence would have been unearthed by the CAA themselves, it would be pretty difficult for them to escape the conclusion that they had not.
On the other hand, a perfunctory cast around in places where they knew there was no evidence, and a factually correct statement that they had found no evidence........
Independence and the avoidance of actual or apparent conflicts of interest are basic and obvious requirements, and in their absence, I'm afraid the outcomes of the investigation are seriously compromised. IMHO