Princess Diana allegedly claimed that she believed Prince Charles was planning “an accident in my car” that would leave her with a serious head injury.

This would allow him “to marry”, she reportedly wrote in a note to her former butler Paul Burrell, just 10-months before she died in a fatal Paris car crash.

Mr Burrell kept the note secret until 2003, when he revealed its existence of the note in his book, A Royal Duty, in which he claimed the princess had handed it to him as an insurance policy.

He wrote that she told him she was going to date it and he should keep it, "just in case".

Written two months after her 1996 divorce from Prince Charles, Diana claimed in the note that she believed there was a plan for “an accident in my car, brake failure and serious head injury”

The following August she was travelling with Dodi Al Fayed in the back of a chauffer-driven Mercedes when it crashed in Paris's Pont de l’Alma underpass.

Mr Al Fayed and chaffeur Henri Paul died at the scene. The princess and Mr Al Fayed’s bodyguard Trevor Rees-Jones were seriously injured in the crash and taken to the Pitie-Salpetriere Hospital.

Diana suffered a heart attack at the scene of the crash and later had her heart massaged in hospital before she died. Mr Rees-Jones survived.

A French inquiry into the crash conducted in 1999 concluded that the chauffeur had consumed a cocktail of alcohol and drugs and had caused the collision by driving too fast.

How the news of Princess Diana's accident was broken on BBC One

Prince Charles' name was originally redacted from Mr Burrell's book, but the full accusation was revealed in the 2007 inquest into Diana’s death at London’s High Court.

It heard that she had written: “I am sitting here at my desk today in October, longing for someone to hug me and encourage me to keep strong and hold my head high."

She also claimed that both she and Camilla Parker-Bowles was being used as "a decoy" by her ex-husband, who she said really wanted to marry Prince William and Harry’s former nanny Tiggy Legge-Bourke.

“This particular phase in my life is the most dangerous – my husband is planning ‘an accident’ in my car, brake failure and serious head injury in order to make the path clear for him to marry Tiggy," she wrote.

Diana: a life in pictures Show all 20 1 /20 Diana: a life in pictures Diana: a life in pictures Diana arriving on 4 October, 1990 for a charity gala at the Departmental Auditorium in Washington Kevin Larkin/AFP Diana: a life in pictures Diana and Prince Charles at their wedding St Paul Cathedral 29 July 1981 AFP/Getty Images Diana: a life in pictures Prince Charles and Diana at the memorial to the British Gloster Regiment outside Seoul. The Royal couple were on a four-day official visit to Korea AFP/Getty Images Diana: a life in pictures Diana listens to a senior nun of the Missionaries of Charity at the house of Mother Teresa in Calcutta on 15 February, 1992 Diana: a life in pictures Diana, Princes William and Harry applaud during the Wales vs France Five Nations Cup match at Cardiff Arms Park on 1 February, 1992 Jean-Pierre Muller/AFP Diana: a life in pictures Diana wearing a heavy duty protection vest and face shield, accompanied by a mine-clearing expert of the Halo Trust 15 January 1997 during her visit to the mine fields near Huambo, Angola AFP/Getty Images Diana: a life in pictures Diana waves to the crowd as she arrives at the Cité de la Villette in Paris on 14 November, 1992 during a three-day visit in France Pierre Verdy/AFP Diana: a life in pictures Diana visiting Khufu, the great Pyramid in Giza on 12 May 1992 Manoocher Deghati/AFP Diana: a life in pictures Diana departs her London health club, 20 November 1995 AFP/Getty Images Diana: a life in pictures Diana listens to a young boy with learning difficulties on 13 November, 1992 during her visit to a school in Paris Joel Robine/AFP Diana: a life in pictures Ronald and Nancy Reagan welcome Diana and Prince Charles to the White House Don Rypka/AFP Diana: a life in pictures Diana and Prince Charles watch Indonesian tribal dancers in Yogyakarta, Indonesia on 5 November 1989 Kazuhiro Nogi/AFP Diana: a life in pictures Diana talks to amputees at the the Neves Bendinha Orthopedic Workshop on the outskirts of Luanda on 14 January, 1997 Joao Silva/AP Diana: a life in pictures Diana with the royal family outside the London Clarence House residence on 4 August 1989 Johnny Eggitt/AFP Diana: a life in pictures Diana and Prince Charles arrive at the church for the funeral of Earl Spencer, Diana's father, who died on 29 March, 1992 Martyn Hayhow/AFP Diana: a life in pictures Diana chats with 15-year old landmine victim, Bosnian muslim girl Mirzeta Gabelic, in front of Mirzeta's home in Sarajevo Hidajet Delic/AP Diana: a life in pictures Diana attending the France-Wales Five-Nations' tournament match on 21 January, 1995 in the grandstand at the Parc des Princes Jean-Pierre Muller/AFP Diana: a life in pictures Diana flanked by tennis players – America's Michael Chang and Sweden's Jonas Bjorkman – during the awards ceremony at the Hong Kong Open on 23 April, 1995 Emmanuel Dunand/AFP Diana: a life in pictures Diana, Prince Harry, and Prince William gather for the commemorations of VJ Day, 19 August 1995, in London AFP/Getty Images Diana: a life in pictures Diana and Jemima Khan, wife of Pakistani cricketer Imran Khan, attend a variety show 22 February 1996 in Lahore Saeed Khan/AFP

At the inquest, the validity of the letter was questioned by one of Diana’s closest friends, Lucia Flecha da Lima, who claimed Mr Burrell could have forged the letter.

Described as one of Diana’s confidantes, she told the court she did not believe the princess had feared for her life.

“Paul Burrell was perfectly capable of imitating Princess Diana’s handwriting. I don’t believe she was fearing for her life, especially from Prince Charles, the future king of your country,” she said.

Asked whether he thought Prince Charles could have planned the princess’s death, Mr Burrell also said it was “impossible”.

“I could not possibly see the father of her children murdering her,” he said.

He told the inquest that “I can’t begin to believe” the princess and Al Fayed were murdered. Knowing the members of the Royal Family as I do, and knowing them so well, I think that’s impossible.”