Brian,
There were many witnesses in NI, both Military and Civil, who had to be interviewed to assess whether the crash had been caused by hostile action.
That having been said, his initial evidence was fairly straightforward. The problem I have is that his evidence is not consistant and that, far from being the "Lone Yachtsman" as he was described because of his original evidence, he was manoeuvring his yacht around fishing vessels and had a crewman.