By Peter Hunt
BBC royal correspondent
This is a defining moment. The core team of 10 British detectives, led by Lord Stevens, were set their task back in 2004 by the then royal coroner, Michael Burgess.
His instructions were simple. He wanted to know whether Princess Diana's death was, as he put it, anything more than "the result of a sad, but relatively straightforward road traffic accident in Paris."
There have been many conspiracy theories about the couple's deaths
Like the French police officers before them, the Metropolitan Police have come to the same conclusion: the princess and Dodi Al Fayed died because their chauffeur Henri Paul was drunk, and driving too fast.
But with the ink barely dry, the hole picking will begin.
Doubts will be raised on the internet and by Dodi Al Fayed's father, Mohammed Al Fayed.
Gone is the time when a report by a distinguished establishment figure could be published and universally accepted.
It may be challenged in the courts. And any suggestion of "moving on" or "drawing a line" under the princess's death is wishful thinking.
Her inquest has yet to take place. Nine years after the accident, and we still do not have a date for the full hearing.
The delay has been caused by the initial French investigation; the subsequent Stevens' inquiry; and various legal proceedings, in several countries, brought by Mohammed Al Fayed.
But the often dormant process, does finally have a sense of momentum.
Dodi Al Fayed died in the crash while Princess Diana died in hospital
Today's report is a major step forward.
There will be a preliminary hearing in January.
Lady Butler-Sloss, the deputy royal coroner who is now in charge, has reversed her earlier decision to meet behind closed doors.
The hearing next year will have to get to grips with some key issues including whether there will be a jury; whether there will be a joint or separate inquests for Princess Diana and Dodi Al Fayed; and whether the royal coroner is the right person to be running the show in the first place.
Since 1997, it has been argued the royal coroner should be involved because, after her death, the princess's body was moved to the chapel in St James's Palace which is within the district of the Queen's Household.
Mohammed Al Fayed's side has maintained the royals stripped Princess Diana of her HRH status and only embraced her in death, rather than in life.
The royal coroner - a position which has existed since the 12th century - is responsible for inquests on people whose bodies are lying within the limits of the monarch's palaces.
There were only eight such inquests in the 20th century.
The last one was in 1986 into the death of a woman who had died in a fire at Hampton Court. It was thought she could have knocked over a candle she always took to her bedroom.
The hearing took place in the banqueting and reception rooms of St James's Palace where witnesses sat on gilded chairs to give evidence and the coroner was positioned at an antique desk.
On the question of a jury at a royal inquest, the law is clear. There is no "wiggle" room.
This is a long way from the independent public inquiry Mohammed Al Fayed has tirelessly campaigned for
It states: "The jurors on an inquest held by the coroner of the Queen's household shall consist of officers of that household".
So, Lady Butler-Sloss faces an unenviable task.
She either sits on her own - and runs the risk of being accused of presiding over an establishment whitewash - or she has a jury which is made up of the Queen's senior employees.
This is just one of the many hurdles the former senior judge has to clear in advance of the inquest taking place, presumably before the 10th anniversary of Princess Diana's death in August 2007.
When it does convene, it will be a limited fact-finding inquiry designed to establish who the deceased was; when and where the death occurred and how it was caused.
This is a long way from the independent public inquiry Mohammed Al Fayed has tirelessly campaigned for.
Since 1997, two contradictory responses to Princess Diana's death have become established.
On the one side, the French and now the British authorities have concluded, after detailed study, that the princess died in a road traffic accident.
On the other side, Mohammed Al Fayed and his supporters insist Princess Diana was murdered by British intelligence because she was going to marry Dodi Al Fayed, who was a Muslim.
Nine years on and two reports later, these positions are entrenched and will never be reconciled.