New DNA tests on blood samples from the French chauffeur who was driving Diana, Princess of Wales, on the night of her fatal crash, prove beyond doubt that he was drunk, according to a BBC investigation.

French authorities carried out new checks on the blood taken from Henri Paul to prove his original samples could not have been switched, according to the documentary.

They were ordered in response to attempts by Mohamed Al Fayed, whose son Dodi also died, to prove that the blood samples of Mr Paul had been deliberately switched as part of a British establishment plot to attribute blame to the driver who was also killed in the 1997 Paris crash.

An investigation by the French authorities concluded in 1999 that Mr Paul caused the crash by driving too fast while drunk. A profile taken from Mr Paul’s blood samples was found to match his parents’ DNA, meaning they could not have been switched, a source told the BBC.

The revelation comes as Lord Stevens of Kirkwhelpington prepares to publish his long-awaited police investigation next week into Diana’s death.

How Diana Died: The Conspiracy Files will be broadcast on BBC Two tomorrow at 9pm.

Explore UK News

• Crime News

• Education News

• Health News

• Scotland News

Times Recommends

• Alex Rider exclusive: Incident in Nice
• Green & confused: do energy-saving bulbs work?
• Let’s skip lunch, say the hungry generation