by SUE REID, Daily Mail

The explosive publication of Diana's letter predicting her own death can only fuel the conspiracy theories that have refused to disappear since the tragedy.

As the British and French authorities continue to maintain a stubborn silence, these theories - however unpalatable - will be given a degree of credence by yesterday's revelation.

Whatever the truth, the events surrounding the events of August 31, 1997, are riddled with mystery and inconsistency.

The Daily Mail has shone a spotlight on the days before and after Diana was found lying seriously injured on the back seat of the Mercedes, her life slipping away, her boyfriend Dodi Fayed already dead by her side.

Many of those involved in the aftermath of the crash will still only talk in the strictest confidence, perhaps fearful of being branded conspiracy theorists.

Others believe what they have to say is of vital importance but complain that few have been willing to listen to it.

Here are some of the crucial answered questions from that night six years ago.

Why was the chauffeur so flush with cash?

The driver of the Mercedes, Henri Paul, was being paid just £20,000 a year at the time of his death. Yet he was found to be unexpectedly wealthy.

As deputy head of security at the Paris Ritz, Paul had accumulated an astonishing pot of gold - £102,000 in 13 different bank accounts.

In the pocket of the grey suit in which he died, police found £2,000 in cash - more than he

earned in a month. In 1997, alone he had paid £4,000 cash into his accounts on five occasions. He was spending £600 a week on flying lessons.

There are two other disturbing issues about Paul. The renegade intelligence agent Richard Tomlinson claims to have seen his name in MI6 files. And on the evening of Diana's death, he mysteriously disappeared for two hours before reappearing at the Ritz to take the wheel of the Mercedes.

Why did the CCTV look the wrong way?

The CCTV cameras inside the Alma Tunnel where the crash happened were, according to sources, turned inwards to face the wall on the night of August 31.

They would thus have been unable to record anything of the collision, the people or the vehicles there at the time or during the tragic aftermath.

Not until dawn on Sunday, September 1, as Diana's body was being prepared for its return to Britain, were the cameras turned to face the traffic.

If this seems strange, so, too, was Paris officials' decision to send the green vehicles of its cleansing department into the tunnel only seven hours after the crash. Their efficiency at spraying the whole area with disinfectant expunged for ever all forensic evidence remaining at the crash site.

Why did the 'drunk' driver have a healthy liver?

More clues about what happened in Diana's final hours lie today in a small medicine bottle in a refrigerator in Paris. It contains a small sample of blood taken during the post-mortem examination on Henri Paul.

Further crucial evidence is contained in 27 confidential, buff-coloured files in the Paris offices of the French judge Herve Stephan, who first investigated the Princess's death.

French authorities have always insisted a combination of alcohol and high speed provoked the crash in which only the Princess's bodyguard, Trevor Rees-Jones survived.

They have let it be known that Paul was an alcoholic who was "as drunk as a pig" when he left the Ritz to drive Diana and her lover back to Dodi's apartment half a mile away.

Two medical experts, Dr Gilbert Pepin and Professor Dominique Lecomte, said the chauffeur was twice over Britain's legal drink-drive limit when he took the wheel.

Yet only three days before the crash, Paul passing an intensive medical examination for flying lessons which showed no signs of alcohol abuse.

Was there a mix-up at the morgue?

That phial of blood remains at the heart of the controversy. For it suggests something else quite extraordinary: That Paul had breathed in a deadly quantity of carbon monoxide before he died.

It was equivalent to the amount inhaled by a suicide victim who places a rubber hose through a sealed window of a car to gas himself.

Such a vast inhalation of the poison would have rendered him visibly disorientated, probably unable to stand unaided. It is possible he would have actually been unconscious.

Yet Paul can be seen on CCTV footage from the Ritz that evening alert, smiling jovially and even bending down to tie up his shoelace.

He was killed instantly in the crash. There is no way he could have then drawn breath and inhaled any poisonous exhaust gases in the wrecked car. Mercedes, for their part, insist their airbags do not contain the gas.

Significantly, Dodi's body contains no carbon monoxide. Unofficially, even Judge Stephan has called the presence of the gas a complete enigma.

What if the blood in the bottle containing the alarming readings, now lodged with the French legal authorities, is not really Henri Paul's? Could he have been completely sober as his parents maintain?

That weekend 23 other bodies were taken to the Institut Medico Legal mortuary where Paul lay. Had one of the dead committed suicide by drinking heavily or inhaling exhaust fumes?

Was there a muddle? Or was it a deliberate mix up?

Why did the ambulance take so long?

As Henri Paul and Dodi's bodies waited to be taken to the mortuary at 12.40am on the Sunday morning, Diana was still alive. Three amblances arrived to find she had a torn pulmonary vein in her chest and blood was seeping into her lungs.

One ambulance with four paramedics - never traced by the French authorities - stretchered her on board their vehicle.

The vehicle took the best part of an hour and a half to reach the nearby Pitie-Salpetiere Hospital. On its way it passed two other clinics which could have treated her.

The ambulance stopped twice at the roadside, apparently to give Diana emergency treatment for failing blood pressure, the second time just 300 yards from the hospital.

By the time she arrived it was too late to save her. She was to die of an injury which was life threatening but not necessarily fatal.

When Ronald Reagan was shot, his pulmonary vein ripped open. But swift hospital attention allowed him back to presidential duties in one month.

Was the Uno driver another victim?

The white Fiat Uno which clipped the Mercedes in the tunnel, causing the crash, was driven by a royal paparazzo called James Andanson.

It took two weeks to trace him after the Fiat was discovered for sale in a Paris garage. The paint on the wrecked Mercedes matched exactly the paint from its tailgate.

Andanson insisted he was at home, in central France, during the early part of the night Diana died. He spun a yarn about flying out of the country through Orly Airport half an hour before she took her last breath at 4am. He produced a petrol receipt to endorse his presence near the airport. But that did not prove he was not in the Alma Tunnel a few hours before.

Andanson, who was never reinterviewed by French investigators, apparently committed suicide in strange circumstances two years later. His body was found in a burned-out car, 100 miles from where he had told his family he was travelling that day. It was locked from the outside.

Who were the masked raiders?

A month later, Andanson's offices in Paris - at the French HQ of the photo agency SIPA - were raided by three armed men in balaclava. They shot a security guard in the foot, held screaming staff hostage for three hours before leaving with laptops, hard disks and cameras. The staff's frantic calls to the police went unheeded.

Could the security services have been involved? Renegade MI6 officer Tomlinson, who was sacked by British intelligence, has claimed they use paparazzi because of their skills at tracking the whereabouts of high profile "targets". Was Andanson one such agent?

Was the Princess pregnant?

This is a persistent rumour fuelled by Diana having told

close friends during the Mediterranean holiday prior to her trip to Paris that she had some exciting news.

Because she was a British citizen, no autopsy was carried out on her in France. Yet her body was embalmed from the waist up by Professor Lecomte at the hospital in the late morning of her death in an event that has never been explained satisfactorily by French authorities.

This broke French law, which bans embalming if another post-mortem is to be carried out because formaldehyde fluid used in the process corrupts some toxicological tests.

One of these tests is for pregnancy. The formaldehyde used in embalming the Princess would have ensured any subsequent tests on Diana would have given a false "positive" pregnancy reading.

Whatever the motive for embalming Diana it destroyed forever all evidence which would have revealed - one way or the other - if she was expecting Dodi's child.

Who was the shadowy figure?

Why did the Mercedes head in exactly the opposite direction from Dodi's apartment when it left the Ritz? Henri Paul knew Paris intimately and the correct route was along the wide Champs Elysee.

If he had made a navigational error, why did he not turn back by using a slip road before the tunnel?

One eye witness claims this route was blocked by a helmeted rider on an unmarked motorbike.

Was Paul in the pay of the British and French secret services? Was the bike placed there to make sure the royal party took that fatal route?

Perhaps an inquest into Diana's death would start to unravel the extraordinary enigma.

Last summer, royal coroner Michael Burgess promised to hold one in the near future. A day later he changed his mind and said no date could be set.

In the light of what he knew, Paul Burrell may not have been surprised by that sudden change of heart. Nor, we have to presume today, would Diana have been.