I fully agree with you re the effectiveness in general of HM Coroners. It took an 800 year old institution to tell one that is still now less than 100 years old, "There is something wrong with your bloody aircraft!".
My point is that dedicated as they might be to searching out the truth, if a Department of State is dedicated to obscuring that truth, that it alone holds all the information relating to a fatal accident, and ensures that its version and only its version is what is available to the Court, then the truth is very unlikely to emerge no matter how ungullible the Coroner.
The MOD is the problem, and in the matter of Military Air Safety has to be divested of its strangle hold over Regulation and Investigation. An independent MAA would then have no more reason to mislead a Coroner than the CAA would, for instance. We might then look forward to honest witnesses and proper verdicts.