Piston Broke, glad you can see things more clearly now. The crew were put in a situation that not many would have escaped from. If their radio navaids were not available due to their very low altitude there would have been no way of cross-checking an erroneus GPS output. A Dead Reckoning plot is next to useless over the sea - there are no track or timing check features apart from the coast - and they hit that. Over the sea in poor conditions it is easy to get a false impression of groundspeed and rate of closure. It is quite probable that they were unwittingly fully IMC, not realising they had actually coasted in until seconds before impact. Was the intercom u/s? (one of the switches in the wreckage was found in the emergency position). If the normal intercom failed just before coasting in it is quite possible that vital crew co-operation broke down at this critical moment, especially as the crew were possibly not so familiar with the switchery of this type as that of the HC1.
The passengers were of extremely high value in the anti-terrorist role (which is presumably why such a previously highly regarded crew was nominated to fly them). It was a poor management decision to "put all the eggs in one basket", especially as the basket was known to have at least one hole in it. Was this internal politics trying to show that there were really no problems with this unproven new aircraft?. When it all went terribly wrong was it perhaps more convenient to blame the dead crew rather than where it perhaps really belonged, at a senior management level?
In any event, there is so much doubt over the circumstances that it was unreasonable to apply the spiteful stigma of "Gross Negligence", especially as this was not the findings of the RAF's own Board of Inquiry. If we can all see this verdict is open to reasonable doubt then why won't the MOD? Is there a can of worms waiting to be opened? "Cause not known" would have been more satisfactory and would not have caused so much extra grief to the breaved.
The following might be considered by any future enquiry:
1. Who was responsible for ordering the crew to fly in these circumstances?
2. Who was responsible for the "Gross Negligence" verdict?
A correlation between anwers 1 and 2 would not be a great surprise to many of us.