I must have missed the bit about a sum of money being found and not a lot of good to him dead. If Henri Paul had been in on a plot to kill her, don't you think he would have worn a seatbelt, to protect himself in order to spend the money? from the evidence given by the MI services, they clearly didn't think she was worth watching, so that could have been in Diana's imagination, built upon by the media and conspiracy theorists.
I just don't believe it would be possible to orchestrate all the players that would need to be involved, in such a short time, most assasinations are carried out smoothly, by relying on the victims routine.
Dodi could have decided to leave by the front exit, they could have decided to pose for the cameras, as they had been doing most of the week, why did Dodi decided not to on this evening? They could have driven at a normal speed.
MI6 would have to have involved so many people, at very short notice, any one of whom could, since the crash have talked. Nobody has come forward to say that they saw anyone 'hanging about' waiting for the mercedes and all Diana had to do to save her life, was wear a seatbelt.