I've read about it over the years and some things don't really add up, IMHO. I certainly don't subscribe to the wild theories that Hess was on board or even a long held rumour that dozens of foreign banknotes were found by those retrieving what was left of the bodies.
There seems to have been a lot of documentation that authors have tried to access over the years on the accident that has conveniently gone missing. Access has been denied to the Royal archives.
The one person who survived the crash, Flt Sgt Jack, tucked away in the tail of the plane, refused to speak about the incident for the rest of his life. (He died in 1978.) While he was injured and in hospital following the crash he was visited by two very senior RAF officers. They paid him a private visit.
The one thing he did say as an old man was that he thought there was no pilot error. (The pilot, who died, and the air crew, were very experienced.) The Duke was an Air Commodore but was not very experienced at flying aircraft.
The plane veered inexplicably away from the planned flight path quite early in the flight. There was poor visibility and where they crashed was hilly.
It is said that at the time friends of the Duke of Kent were staying at Langwell House, close to the site of the crash.
The last known message from the fight deck was "Let's go down and have a look...."
The Duke was a man who liked taking risks. I have no evidence at all to back up my theory, apart from the above scraps. It's all speculative. However, I believe it may well be possible that the Duke of Kent was at the controls of the plane and intended to buzz Langwell House, giving his friends and himself a laugh. He wasn't terribly experienced, and the plane crashed and burned.