Ever since her death in 1997, conspiracy theorists have sought to prove that Princess Diana's death was no accident.

Recent polls have indicated that 27% of the population and 85% of readers of a national tabloid believe Diana was murdered.

Possible motives cited for such a murder are the ‘facts’ that Diana was about to get engaged to Dodi Al Fayed and that she was pregnant with his child.

Persistent rumours surrounding her fatal car crash in Paris include claims of a mysterious 'flash' before the collision, charges that the French emergency services were deliberately incompetent and allegations of a mix-up of samples at the French autopsy.

Now, as the inquiry into her death is opened and adjourned, Channel 4's award-winning investigative journalist Martyn Gregory investigates the various conspiracy theories and looks at who stands to gain from the perpetuation of certain myths.

Gregory has obtained new documents from the secretive Paris crash investigation and secured an exclusive TV interview with the head of the French police inquiry.

The programme also includes interviews with Diana's close friend, Rosa Monckton, and the mortuary manager present at her post-mortem, who speaks for the first time on British TV.

Vote Results 5 February 2004
Did you think Diana's death was an accident, or part of a conspiracy ?

In a vote held on the night of the programme 78% of you believed Diana's death to be part of a conspiracy and 22% of you thought it was an accident.