Pheasant, the last thing I want to get involved in here is a willy waiving contest and general yah-boo about "your lot sucks whilst ours is great". I find your statement:
I am also struggling to recall an RN air accident where airworthiness or the Military Airworthiness regime run by the RN was in any way a significant factor in the accident.
to be rather confusing. It is my understanding that
all UK military aircraft are essentially subject to the same Airworthiness regime, ie the MOD's, hence no single service can be exempt from deficiencies in that regime. The MOD has many deficiencies in its Airworthiness regime!
As to the Sea King accident, I understand it involved two Sea King aircraft of the same Mk. being involved in an almost head on mid-air collision in hazy conditions. I also understand that the fitting of the forward HISL's on that Mk was such that pilots could be dazzled by them in such hazy conditions. Thus it is probable that neither aircraft was operating its forward HISL at the time of this accident. That would seem to constitute a "significant factor" in my book, but one which the BoI discounted by performing its own ad hoc trials and thus finding that it was not significant after all!