UK- It has taken more than 90 days, 270 witnesses and a bill of £10 million to slay the obsessive conspiracy theories of one man. And in the end yesterday, a jury discarded the soft option of accidental death and placed much of the blame for the deaths of Diana, Princess of Wales, and Dodi Fayed on the shoulders of one of Mohamed Al Fayed’s own employees.

The Princess and Dodi were unlawfully killed by a combination of their drunk driver, Henri Paul, and the paparazzi who were chasing their car, the jury at their inquests decided.

It was a disastrous outcome for the owner of Harrods, whose allegations of a murder plot masterminded by the Duke of Edinburgh were rejected decisively by the coroner for complete lack of evidence. It was a damning indictment, too, of the pursuing photographers who must accept an equal share of the blame. Even the dead do not escape censure. The couple might have been alive today, the jury decided unanimously, had they been wearing their seatbelts.

Lord Justice Scott Baker, who presided over one of the longest and highest-profile inquests in British legal history, must hope, along with most of the population, that the verdict will close the book on a ten-year saga.

Mr Al Fayed, 75, who has spent an estimated £15 million from his own coffers, was in Court 73 yesterday afternoon to hear the verdict. He left with a thunderous face, but was uncharacteristically subdued last night as to what, if anything, he would do next. In a statement read by his spokeswoman, he said: “It has been a long fight to uncover the truth. I am not the only person who says they were murdered.

“Diana predicted she would be murdered and how it would happen. So I am disappointed. The verdicts will come as a blow to the many millions of people around the world who supported my struggle.”

By a majority verdict of nine to two, the jury of six women and five men rejected the widely predicted decision of accidental death and took an unexpectedly tough view of the crash in a Paris underpass in 1997. They blamed “grossly negligent driving” by Mr Paul at the wheel of the Mercedes, who was said in evidence to have been driving at twice the speed limit while three times over the French alcohol limit, and by the following pack of photographers desperate for a picture of the Princess and her lover.

Mr Paul is dead and the paparazzi are beyond the jurisdiction of an English court. The only further legal action likely at this stage is the possible pursuit of Paul Burrell, the Princess’s former butler, when he next sets foot in England, to answer questions about possible perjury arising from the evidence that he gave to the inquests.

After hearing evidence for six months, the jury retired last Wednesday and spent a total of nearly 24 hours deliberating five possible verdicts: unlawful killing by Mr Paul, the paparazzi or a combination of both; accidental death; or an open verdict. Lord Justice Scott Baker, the coroner, directed them to ignore Mr Al Fayed’s theories of a murder conspiracy.

Yesterday afternoon the jury passed a note to the coroner asking if he would accept a majority verdict. He said he would but sent them back for another hour to try for a unanimous decision. They failed, and returned just before 4.30 with the minimum permitted split. They were, however, unanimous in their view that two contributory factors to the couple’s deaths were that they were not wearing seat belts and that their Mercedes hit a concrete pillar in the Alma tunnel rather than anything else.

It took the foreman of the jury less than five minutes to read out the verdict. After hearing their decision the coroner thanked them for their remarkable patience and excused them from further jury service for the rest of their lives.

Their decision is more robust than the French judicial inquiry, which recorded a verdict of accident, even though the French authorities issued a statement within three days of the crash that Mr Paul had been three times over the French drink-driving alcohol limit.

Lord Stevens of Kirkwhelpington, the former Metropolitan Police Commissioner who compiled an 800-page report on the deaths, also came to the conclusion of accident, although his principal task was to disprove Mr Al Fayed’s conspiracy theory, which involved not only Prince Philip and MI6, but most of the British and French Establishments.

Last night Lord Stevens welcomed the verdicts as a justification of his inquiry, which cost the taxpayer about £3.7 million.

After the verdicts Mr Al Fayed and his legal team went into a deep huddle, but said afterwards they had not decided whether to seek a judicial review in an attempt to overturn the jury’s verdict.

It was thought last night that any such application would be most unlikely to succeed, especially as Mr Al Fayed, while giving evidence to the hearings under oath, agreed to abide by the jury’s verdict.

Prince William and Prince Harry last night expressed thanks to members of the inquest jury. “We agree with their verdicts and are both hugely grateful to each and every one of them for the forbearance they have shown in accepting such significant disruption to their lives over the past six months,” they said.

They added that they would like to “express our most profound gratitude to all those who fought so desperately to save our mother’s life on that tragic night”.