The truth will out? After six years, date is set for inquest into the deaths of Diana and Dodi

To many people, it was a simple, if tragic, car crash, caused by a drunken chauffeur driving too fast. But some still believe Diana, Princess of Wales, was murdered in a security services conspiracy because she was pregnant by Dodi al-Fayed.

Now, for the first time, an English court is to conduct inquests into the deaths of the Princess and Mr Fayed, which may, or may not, resolve many of the outstanding questions about the events in Paris on the night of 31 August, 1997.

After more than six years of delay, speculation, doubt and conspiracy theories, the inquests will be formally opened next year at hearings which will pave the way for full inquiries. At the inquests, key figures such as Paul Burrell, the Princess's former butler and Mohammed al-Fayed, the owner of Harrods and chief architect of the conspiracy theories, could give evidence.

Michael Burgess, who is Surrey coroner and coroner to the Royal Household, announced yesterday he will open the inquest into the death of the Princess at the Queen Elizabeth II conference centre in central London on 6 January.

Later, he will also open the inquest into the death Mr Fayed in Reigate, Surrey, where he is buried in the grounds of the estate of his father.

Mr Burgess said: "The opening of these inquests has been the subject of discussion and correspondence with the families for some time but because of the complexity of the situation, the final arrangements have taken rather longer to complete than I would have wished.'' Witnesses will not be called on 6 January, but Mr Burgess will outline the procedures, and the nature of the evidence he expects to hear.

The delay was caused, not by an attempt at some sort of cover-up, but simply because the French authorities could not release documentation until all legal proceedings there had been exhausted. An investigation concluded in August, 1999, that the crash was a simple accident caused by the chauffeur, Henri Paul, driving too fast while under the influence of drink and drugs.

The proceedings have since been protracted by repeated legal challenges by Mr Fayed, the main source of claims that his son and the Princess were murdered by the security services because of the closeness of their relationship and the possibility they would marry. He is still campaigning for a full public inquiry, appearing in court in Scotland to put his case this week.

With the decision last month by a French court to throw out a privacy violation civil case, brought by Mr Fayed against three of the photographers who were following the Princess's car the night she died, his challenges in France have in effect been exhausted.

Mr Burgess stressed yesterday that only after he has read the 6,000 pages of documentation assembled by the French investigating magistrate, which he clearly expects to be released to him, will he be able to say whether further inquiries need to be made, whether witnesses will be called and who will be legally represented. He still has the option of conducting both inquests together.

But the question of who is likely to be called remains tantalising, since coroners have considerable freedom in how hearings proceed. Certainly, he could call those with first-hand knowledge of the events, such as the Princess's bodyguard, Trevor Rees-Jones, the only survivor of the crash. He could also call French doctors to give evidence about her injuries, although there may be sufficient information contained in the French report.

While the executors of the Princess are likely to be legally represented formally, the Spencer family has always accepted the more orthodox explanation for her death, unlike Mr Fayed. He will try to raise his theories through his lawyers at the inquest into his son's death, where he is entitled to be legally represented. He cannot be similarly represented at the inquest into the Princess since he does not qualify as an "interested party" and lost an earlier challenge into this ruling.

A spokesman for Mr Fayed said last night that while the development was encouraging, it did not affect his desire for a public inquiry. He said: "The remit of a coroner's inquest is far too narrow. It's merely to determine the cause of death. Some people have said to me he's achieved a breakthrough, but this doesn't affect what's happening in the court in Scotland. This is a matter which requires open public scrutiny on a much broader scale than an inquest can offer."

Mr Burgess could try to avoid creating a platform for Mr Fayed by making the inquest into the Princess a substantive inquiry into the events of the night and simply have a shorter formal hearing for her companion. But this will serve only to fuel the conspiracy theories. Among the many claims are that Paul was an informer for the French and British intelligence services and had large amounts of money in several bank accounts and in his pockets on the night.

The high levels of carbon monoxide found in Paul's blood has also aroused suspicion, with experts saying it would have made him incapable of driving. The conspirators claim his blood samples could have been switched at the mortuary or mixed up.

Other questions centre on why it took more than an hour to ferry the Princess by ambulance to the hospital, and why Paul was heading in the opposite direction to Mr Fayed's apartment when he left the Ritz hotel. The mysterious white Fiat Uno believed to have clipped the car carrying the couple was never traced but James Andanson, a paparazzi who had followed the couple before, drove a similar car which he sold after the crash, although he produced evidence backing his claim that he was not at the scene. Three years ago, he committed suicide.

But coroners are notoriously reluctant to entertain evidence of wider conspiracies in deaths which are in some way difficult and contentious, a category in which those of the Princess and Fayed, must be included.

WHO MIGHT BE CALLED TO GIVE EVIDENCE

Paul Burrell, the Princess's butler
Claims to have received a letter from Diana, Princess of Wales, 10 months before she died, warning of a plot to damage the brakes on her car. Spoke with her on the telephone several times in the days before her death, so could give evidence about her state of mind and her relationship with Dodi al-Fayed.

Trevor Rees-Jones, the Princess's bodyguard
Severely injured in the crash - he was in the front seat - and said he remembers very little about the night, but is the only survivor able to give any details about the car journey.

Mohammed al-Fayed, father of Dodi al-Fayed
Maintains the couple were killed in a security services plot. Cannot be legally represented at the inquest into the Princess, but will be able to ask questions through his lawyer at the hearing. Could be called as a witness at either hearing, but has no first-hand knowledge of the events.

Rosa Monckton, friend of the Princess
On holiday with the Princess in the weeks before her death and could be called to back up her rejection of claims the Princess was having a baby or that she planned to wed Mr Fayed, allegedly the reason for the security service's "plot".

French paparazzi and emergency services
A number of photographers, who were following the car when it crashed, continued to take photographs as the paramedics arrived and treated the couple. Both groups have vital evidence of the last moments of her life.