The long-awaited 400-page report into the death of Princess Diana and her boyfriend Dodi Fayed should - officially, at least - finally set the conspiracy theories to rest.
Lord Stevens, the former Metropolitan Police Commissioner, has concluded that Diana died in a road traffic accident after her driver, who was drunk at the wheel, lost control of the car.
Lord Stevens' report finds no evidence to support Mohamed al-Fayed's claims that the crash was orchestrated by MI6 on the orders of the Duke of Edinburgh. The Harrods boss served notice last night that he intends to step up his campaign with a furious attack on the BBC.
But senior police sources say that Fayed would be ill-advised to question Lord Stevens' independence given his impressive reputation for taking on the intelligence services, Army, police and politicians in his successful inquiry into collusion between the Royal Ulster Constabulary and loyalist paramilitary groups in Northern Ireland.
The key finding contained in the 15-page executive summary of Operation Paget is that Henri Paul was over the legal alcohol limit. This was a major contributing factor in his losing control of the Mercedes after it became involved in a high-speed race with paparazzi on August 31, 1997.
The report will say that paparazzi chasing the car Diana was in contributed to the accident. Although there were errors in the handling of samples taken from Mr Paul on the night of the crash, reports claim that it has now been conclusively proved that the samples that tested positive for alcohol and prescription drugs were those of the driver.
A favourite claim of conspiracy theorists that the samples were swapped by MI6 agents with those of a suicide victim has been disproved by DNA evidence, according to the BBC.
But in a sign of the battles ahead, Fayed launched a bitter attack on the corporation. "The BBC has fallen into a trap," his spokesman said. "The two samples that tested positive for alcohol were not tested for DNA."
Lord Stevens is also said to have disproved the claim that Diana was pregnant after being shown the results of tests carried out 10 days before her death as part of a treatment for pre-menstrual tension.
Tests on the Princess' uterus have provided conclusive proof that she was not pregnant when she died. This supports evidence from Rosa Monckton, the Princess's close friend, who was also interviewed by detectives. Ms Monckton, who had been on holiday with her friend just 11 days before the crash, said the Princess had started her menstrual cycle when the two women were together.
Another Fayed claim, that Diana and Dodi were planning to get married, is also discounted in the conclusions of Operation Paget, the three-year investigation by a dozen detectives which has cost about £3 million ($8.5 million).
But the Harrods boss is set to receive a partial vindication as the report is expected to concede that employees of the Ritz in Paris, where Diana and Dodi were staying at the time, had previously passed information to French intelligence services.
The report is also expected to conclude that Mr Paul was a paid informant for the intelligence services but that he was acting for the French, not the British.
However, the former Metropolitan Police Commissioner firmly rejects claims of MI5 or MI6 involvement in the crash.
A senior police source downplayed the significance of links between the hotel andFrench secret agents. "I'm sure that the intelligence services have informants in the Ritz in London."
It was in that hotel that the Queen celebrated her 80th birthday last Monday with a private party for her 50 closest friends and family. The event - planned two years ago - fell uncomfortably close to the date of the report's publication but it was decided to press ahead regardless.
The Queen has instructed officials not to respond to any claims made by Fayed. Instead, senior members of the royal family plan to present a united front in the immediate aftermath of the document's publication on Thursday.
Prince William's passing-out parade from Sandhurst is seen as providing the perfect opportunity to show that Diana's sons are getting on with their lives almost a decade after the death of their mother.
William was shortlisted for the military academy's sword of honour, presented to the cadet judged to have the most potential.
He is also rumoured to be about to announce an engagement to his girlfriend, Kate Middleton.
These distractions will in the short term help to fight an expected counter-blast from Fayed as the attention moves to the formal inquests that resume in the new year.
Buckingham Palace is braced for the intense media scrutiny that will follow the report. Far from bringing the controversy over Diana's death to a close, the palace knows that the report will inevitably lead to yet another airing of the conspiracy theories.
Lord Stevens' detectives have gone to extraordinary lengths to investigate every lead supplied by Fayed and other parties. Hundreds of witnesses have been interviewed and - as in the case of Mr Paul's blood samples - new techniques have been applied to existing evidence.
The inquiry shipped the car in which Diana died, an S-Class Mercedes, to London from Paris to carry out exhaustive tests, re-creating the incident on a specially designed computer model. The only credible explanation was the same reached by the 8000-word French inquiry - that Mr Paul lost control of his car after it hit the 13th pillar of the Pont de l'Alma underpass.
But a spokesman for Mr Fayed queried claims that Mr Paul had been driving at 100mph at the time of the crash.
"This is utterly and provably untrue. Scotland Yard has acknowledged that it was in fact travelling at about 60mph at the time of the crash," he said. "Incredibly, none of the eyewitnesses to the crash - at least 13 in number - have been seen or interviewed as part of the Stevens investigation.
"No one has been able to trace the two missing cars and at least one motorbike which went into the tunnel at the same time as Henri Paul but have never been seen since."
Attention now switches to the formal inquiries that will resume in the new year. The Fayed camp scored an early victory last week in forcing the initial hearings to be held in public.
Initially Dame Elizabeth Butler-Sloss had ruled that the hearings on January 8 and 9 should be heard in private but backed down in the face of a legal challenge from Fayed.
The retired judge, who took over the case from the royal coroner, Michael Burgess, must first rule whether to sit with a jury or not. Because of the arcane rules, a jury in an inquest by the royal coroner must be made up with members of the Royal Household.
Representatives of Diana's executor Lady McCorquodale, the Queen and Fayed will all be represented at the inquest.
Chronology - Life and times of Princess Diana
July 1, 1961 - Born into an aristocratic family, third of four children of Lord and Lady Althorp.
1977 - Met Prince Charles, heir to the British throne, at Althorp.
February 24, 1981 - Engagement to Charles announced.
July 29, 1981 - Charles and Diana married at St Paul's Cathedral in London.
June 21, 1982 - First child born, William Arthur Philip Louis, known as Wills. Diana suffered post-natal depression.
September 15, 1984 - Second child born, Henry Charles Albert David, known as Harry.
1985 - First reports of marriage difficulties.
1986 - Charles renewed his relationship with Camilla Parker Bowles. Diana developed bulimia nervosa. Royal couple continued public duties but, in private, led separate lives.
June 1992 - Diana - Her True Story, by tabloid reporter Andrew Morton, is published. Diana co-operated in the writing of the book that showed her trapped in a loveless marriage and attempting suicide to attract Charles' attention.
August 25, 1992 - Newspapers publish excerpts of taped telephone conversation between Diana and James Gilby, who called her "Squidgy" and told her he loved her.
December 9, 1992 - Prime Minister John Major announced formal separation of the couple in Parliament.
September 1994 - Princess In Love by Anna Pasternak published, telling of an affair between Diana and cavalry officer James Hewitt. Book condemned but Diana later confirmed she had had an affair with Hewitt and said she adored him.
November 20, 1995 - Diana gave TV interview in which she admitted adultery with Hewitt and said she doubted Charles' ability to handle the responsibility of being king.
December 20 - Buckingham Palace confirmed Queen Elizabeth had written to Charles and Diana urging them to divorce.
February 28, 1996 - Diana agreed to a divorce.
July 12 - Charles and Diana agreed divorce terms. Diana was to get £17 million ($48.99 million) settlement but was stripped of the title Her Royal Highness.
August 28 - Charles and Diana granted a decree absolute ending their 15-year marriage.
August 7, 1997 - First media reports that Diana had found a new love - Dodi Fayed.
August 31 - Diana killed in car crash with Fayed just hours before she is due to return to Britain.