The mechanical details of the most minutely examined car crash in history are brutally simple.
The black Mercedes S-280 driven by Henri Paul and carrying Diana, Princess of Wales, her companion Dodi Fayed and his bodyguard Trevor Rees roared away from the rear entrance of the Ritz hotel in Paris at 12.20am on Sunday August 31 1997.
The car smashed into the 13th pillar of the Alma tunnel, which straddles the dual carriageway running alongside the River Seine, approximately three minutes later.
Had the car not been travelling at 65mph in a 31mph area, had it glanced against the pillar instead of hitting it head-on, or had it bounced off the side wall instead, the shock of the crash would have been less shattering and the occupants of the car might have survived.
Had any of them been wearing seatbelts, they might have stood a better chance.
As it was, Dodi and Paul were killed outright, while Diana and Rees suffered major injuries.
The princess was extricated from the car, treated at the scene and transported slowly to hospital with her heartbeat erratic and her blood pressure flattening fast.
At the Pitie-Salpetriere hospital, she was operated on by Professor Alain Pavie, the president of the French college of cardiovascular surgeons. He discovered huge internal injuries, including a tear the width of a man's fist in her superior pulmonary vein where it entered the heart.
Pavie said he had never seen a patient survive such an injury. Diana was pronounced dead inside two hours.
Professor Thomas Treasure, the president of the European Association for Thoracic Surgery, queried some details of the treatment, but conceded to the inquest there was a "very low likelihood" that she could have lived.
Almost all else in the last ten and a half years has been speculation and theorising.
It has been the subject of major French and Metropolitan police investigations - the latter lasting three years, costing £3.7m and producing an 832-page report in 2006 - and now an inquest lasting six months, costing at least £7m and hearing evidence from 250 witnesses.
Had Dodi Fayed's father, the Harrods owner Mohamed Al Fayed, not been immensely rich, litigious and obsessively convinced from the moment he first heard of the crash, half an hour after it happened, that it was the result of an establishment conspiracy, the whole tragedy might have been laid to rest a decade ago. Fayed has contemptuously rejected any alternative explanations as garbage.
The inquest ostentatiously, and at laborious length, examined all of the conspiracy theories, clearly with the intention of finally settling the matter once and for all, and cross-examined an exotic cavalcade of witnesses.
Diana's complementary therapist and energy healer, her personal masseuse, her acupuncturist and her former butler Paul Burrell, who has made a good living out of his association with her, all turned up.
On examination, the conspiracies crumbled. Several of them originated with and were solely sourced from Fayed himself and, despite all the money he had spent, had no external factual basis at all.
Was Diana pregnant? The only suggestion that she might have been came from Fayed, who said she'd told him in a phone call an hour before the crash - and he had then kept the suggestion to himself until sharing it with the readers of the Daily Express three years later.
There was plenty of evidence that she was not: witnesses attested that she was on the pill and had just had her period.
Was she killed because she was about to marry a Muslim? Fayed said Dodi had told him about their plans in the same phone call, but there were plenty of Diana's friends who said she had told them she needed another marriage "like a rash on the face".
There was also the inconvenient fact she had emerged unscathed from an intense two-year affair with the Pakistani surgeon Hasnat Khan, a man Fayed dismissed at the inquest by saying: "You cannot marry someone like that, [who] lives in a council flat and has no money."
Other allegations had simple explanations: was Diana's body embalmed at the Paris hospital to disguise her pregnancy? No, because it was beginning to deteriorate in the late summer heat.
Was there a conspiracy directed by the Duke of Edinburgh and carried out on his orders by MI6? There was no evidence that there was, and plenty to suggest it was unlikely.
Would the British security service really have dispatched an assassin in an ageing Fiat Uno to take on a high-powered limousine?
And how could they have set up such a plot in the few minutes after the plan to drive the couple back to the Fayed apartment instead of staying at the Ritz was formulated - particularly if the conspiracy involved both British and French security services, the French medical authorities, the police and judiciary in both countries, to say nothing of Tony Blair, the British ambassador, the Queen's private secretary and even the princess's own solicitor.
Fayed was given the opportunity to air all of these allegations, but it was noticeable that his legal team did not pursue them. Practically the only witnesses who endorsed any parts of his claims were his employees or beneficiaries.
The coroner, faced by the apparent zeal of Fayed's closest and most loyal advisers to follow his bidding and conceal inconvenient facts, cast doubt on the evidence of John Macnamara, a former head of security at Harrods, Michael Cole, his former director of communications, and Stuart Benson, his solicitor.
As with many such conspiracy theories, the facts had to be wrestled into line to fit and, if they could not be made to do so, they were either ignored or used to send the plot in a different direction.
Thus Fayed's side originally contended that Paul had not been drinking, when they knew within days of the crash that he had consumed two Ricards in the Ritz bar and had been missing for three hours earlier in the evening after going off duty.
The missing period then came to be ascribed to him being briefed by MI6 about the forthcoming plot.
What may have surprised his legal team was the fact the British establishment turned out in force and on the record to deny Fayed's claims and submit themselves to his lawyers' cross-examination.
No fewer than 11 members of MI6, including its former head, Sir Richard Dearlove, entered the witness box. The witnesses who did not turn up were the French paparazzi, and they did not have to because they remained outside of the coroner's jurisdiction.
In the end, it was the small details that were most telling: the masseuse Myriah Daniels testifying that Henri Paul had driven recklessly from the airport earlier in the day: "With all due respect he was probably a very nice man but he was shit as a driver."
And the revelation of how sad and empty Diana's life was during those last months: she was at a loose end because it was the first summer she was spending without her sons, who had been dispatched to Balmoral.
When she returned from her holiday with Dodi, she only went to Paris because she was relying on him to give her a lift back to London in the Fayed family jet.
Fayed has sat in court throughout the inquest, glaring impassively. A bereaved father, yes - but also a vengeful and controlling one surrounded by acolytes, seemingly anxious above all to deflect criticism from his own responsibility for what happened.
The inquest heard that Dodi, at the age of 42, rarely took any decisions without calling his father first.
The bodyguards who reluctantly went along with the plan for the couple to be driven home by Paul were told that Fayed Sr had okayed it, and they knew better than to question his instructions.
Diana had already come up with a nickname for the boss on her final holiday. The inquest heard that she said: "God's calling" as she handed the mobile phone to Dodi for the umpteenth time.