After three years and £3.7m, Stevens finds no cover-up and no conspiracy

A £3.69m police inquiry into the allegation that Prince Philip and MI6 colluded to murder Diana, Princess of Wales, and her lover, Dodi Fayed, has concluded that there was "no conspiracy and there was no cover-up".

The three-year investigation by a team of detectives confirmed the findings of an earlier French inquiry that the death was caused by a drunk chauffeur who lost control of his speeding car in a Paris underpass.

The 832-page Operation Paget inquiry report, published yesterday, comprehensively debunked most of the conspiracy theories built up around the world's most infamous car crash.

The man behind the majority of the allegations, Mohamed al-Fayed, the father of Dodi, attacked the investigation into the August 1997 crash, describing it as "garbage" and a "cover-up". The Harrods owner maintained Diana and Dodi were assassinated on the orders of a member of the Royal Family.

But Lord John Stevens, the former Commissioner of the Metropolitan Police who headed the 12-strong team of detectives, concluded that the crash was a "tragic accident" and that there was no evidence of a murder conspiracy.

The inquiry report did reveal, however, the key role played by a mystery driver, whose Fiat Uno appears to have triggered the crash after it collided with the Mercedes being used to transport the Princess. It also provided a fascinating insight into the Princess' state of mind, her relationship with the rest of the Royal Family and with Dodi - who may have been planning to propose to her on the night of their death.

The report concluded that the driver, Henri Paul, who was also killed, was drunk and driving at excessive speed. He had an alcohol level of about 1.74 grams per litre at the time of the crash - about twice the British drink-drive limit.

The black S280 Mercedes was being driven through the Pont de l'Alma tunnel in Paris at about 61 to 63mph - twice the speed limit for that section of road.

Lord Stevens said: "Our conclusion is that, on all the evidence available at this time, there was no conspiracy to murder any of the occupants of the car. This was a tragic accident ... There was no conspiracy and there was no cover-up."

It also scotched several allegations, including the suggestion that the Princess of Wales was pregnant, or interested in marrying Dodi.

Prince William and Prince Harry welcomed the "conclusive findings" and called for speculation surrounding their mother's death to come to an end.

The brothers were briefed about the report - which included graphic witness accounts of Diana as she lay injured in the car's wreckage - by Lord Stevens on Wednesday night.

Diana, 36, Dodi, 42, and Paul were all killed when their Mercedes crashed into the 13th pillar of a Paris underpass in the early hours of 31 August 1997. Their bodyguard, Trevor Rees, formerly known as Mr Rees-Jones, was the sole survivor. None of the occupants was wearing a seat belt.

The findings fall short of blaming the paparazzi for chasing the Princess and her partner, but the report makes it clear they were hounding the couple throughout their stay in Paris. The attention became so intrusive that Dodi cancelled a planned meal on the night of the accident and returned to the Ritz hotel. It was from there that the hotel's deputy security manager, Mr Paul, drove them later that evening.

Blood tests showed that he was two times over the British drink-drive limit, and had recently been taking drugs for alcoholism. It was also confirmed that he was an informer to the French security services.

The report highlighted for the first time the significance of a collision between the Mercedes and a white Fiat Uno shortly before the accident. Reconstructions found that the crash started just outside the tunnel.

The report concluded "that the driver of the Mercedes, Henri Paul, was between 60 and 105 metres from the beginning of the underpass when he started to perceive the hazard presented by another vehicle, such as the Fiat Uno, and thus saw the need to take avoiding action.

"In other words, the chain of events that led to the fatal 'accident' started some way from the entrance to the underpass. By the time the Mercedes approached the thirteenth pillar, the result was inevitable, ie the Mercedes would collide with the pillar."

White paint was found on the wreckage of the Mercedes, but despite a massive search by the French authorities, the Fiat Uno and its driver have never been found.

It also emerged that Dodi had selected a ring and may have been planning to propose to the Princess on the night they died. But friends of Princess Diana told the inquiry that she had no intention of marrying Dodi.

Despite claims by Dodi's father, after the accident, that the Princess was pregnant, forensic tests showed she was not expecting a child.

Other conspiracies that the Paget inquiry team examined and either rejected or found no evidence to support were the suggestion that MI5 and MI6 had been following or bugging the Princess while in Paris; that the American secret services had been listening in on her telephone conversations; that flashing lights inside the underpass contributed to the crash; that the tunnel's CCTV system had been deliberately disabled; and that the Princess was embalmed to hide her pregnancy.

But Lord Stevens did concede: "There are some matters... [where] we may never find a definitive answer."

The main points

* There was no establishment conspiracy, specifically by MI6, to murder Diana, Princess of Wales .

* Forensic tests on the Princess's blood showed no trace of pregnancy hormones.

Dodi Fayed may have been planning to propose but the "weight of evidence" suggested the Princess was not intending to become betrothed to him, including testimony from Prince William.

Diana's Mercedes made a "glancing blow" with another car - a white Fiat Uno - in the Paris underpass. but the vehicle was never traced.

Diana feared the Prince of Wales was planning an accident in her car. But the report found no evidence to support this.

There was no evidence of any link between Prince Philip and the Security and Intelligence Service (MI6).

Diana's driver, Henri Paul, was speeding and had an alcohol level of around 1.74 grams per litre - twice the British drink-drive limit.

The unanswered questions

Who was driving the white Fiat Uno?

A white Fiat Uno "glanced" the side of the Mercedes shortly before it entered the Alma underpass. Specialists at the UK's Transport Research Laboratory wrote: "The driver of the Mercedes, Henri Paul, was between 60 and 105 metres from the beginning of the underpass when he started to perceive the hazard presented by another vehicle, such as the Fiat Uno, and thus saw the need to take avoiding action."

What happened to Henri Paul's blood samples?

There is no reasonable explanation for why the number of blood samples taken on 31 August 1997 was changed from five to three.

Was Dodi Fayed going to propose to Princess Diana on the night they died?

Mohamed al-Fayed claims his son had wished to return to his apartment to present the Princess with an engagement ring he bought on the day of the accident. But friends claim Princess Diana did not know about the ring or about the proposal.

Who is the mystery woman that the infamous Princess Diana letter supposedly named as the person the Prince of Wales wanted to marry?

Paul Burrell, the royal butler, produced a note in which the Princess claimed Prince Charles was planning an accident in her car so that he could marry. The report stated: "The Princess did name a woman in her note. It was not Camilla Parker Bowles. Operation Paget knows the identity of the woman named." The Prince of Wales said the woman was just a friend.