'Dynamite' secret Princess Diana tapes in which she talks about her sex life will finally be aired

Controversial tapes in which Princess Diana talks about her private life are to feature in an upcoming documentary on Channel 4.

The tapes, which have never been broadcast on British television, show Diana talking candidly and informally about her troubled marriage to Charles.

The footage was recorded by her speech coach Peter Settelen and have been described as ‘dynamite’ by the producer of an upcoming documentary on Channel 4, which will air the clips close to 20th anniversary of Diana’s death.

The tapes, made between 1992 and 1993 and recorded at Kensington Palace, were only broadcast once – on NBC in the US in 2004.

Diana hired Mr Settelen between to help with her public speaking voice, following her collaboration with author Andrew Morton on a biography, and ahead of her bombshell Panorama interview in 1995.

The footage shows the princess rehearsing her speaking voice and reflecting at length about her life.

Diana talks about her marriage to Charles in the tapes (Picture: PA)

The documentary, titled Diana: In Her Own Words, is being made by freelance producer and director Kevin Sim, who has previously called the footage ‘dynamite’.

In the tapes, Diana says that she and Prince Charles only met 13 times before they got married.

She also talks about the couple’s sex life, saying they had sex ‘once every three weeks’ – and her anger at his relationship with Camilla Parker Bowles, now the Duchess of Cornwall.

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On Monday, ITV screened its own Diana documentary, featuring contributions from her sons, the Duke of Cambridge and Prince Harry.

Channel 4’s head of factual, Ralph Lee, said the upcoming programme is an ’important contribution to the historical record’.

He said: ‘The tapes, which show a relaxed and off-duty Diana, are hugely illuminating about her personality, humour and charm.

‘Combined with historical context and interviews with her closest confidants, this film provides a nuanced, multi-layered portrait of the most famous woman in the world and a mother who has shaped the future line of the royal family.

‘This film gives Diana a voice and places it front and centre at a time when the nation will be reflecting on her life and death.

‘It is her account of events both private and public and is an important contribution to the historical record.’

Diana and her sons Harry and William, who took part in an ITV documentary about her life (Picture: Rex)

The tapes were returned to Mr Settelen in 2004 after a lengthy dispute with Diana’s family, headed by her brother, Earl Spencer, who said the footage belonged to them.

A batch of some 20 videos had been held by Scotland Yard after being seized in a January 2001 raid on ex-royal butler Paul Burrell’s home.

The content of the tapes was regarded as so sensitive that the prosecution agreed not to use them in Mr Burrell’s Old Bailey trial, which collapsed in 2002.

The tapes were later sold to American broadcaster NBC for an undisclosed sum and excerpts were broadcast in 2004, showing Diana talking of how Charles ‘leapt upon’ her to kiss her at the start of her relationship.

She also told of running to the Queen after she became convinced that Charles had resumed his romance with Camilla.

She said: ’I went to the top lady and I’m sobbing. And I said, “What do I do?” (The Queen) said, “I don’t know – Charles is hopeless”.’

Other admissions from the Princess included how she was deeply in love with a royal protection officer – presumed to be Barry Mannakee.

The bodyguard was killed in a motorbike accident and Diana revealed she believed he was ‘bumped off’ because of their affair.

In 2004, the screening was met with criticism amid calls for the tapes not to be shown for at least 100 years.

Sir Teddy Taylor, then Tory MP for Rochford and Southend East, appealed to broadcasters’ ‘sense of decency’ not to air the tapes while Diana’s sons were still alive.

The Channel 4 film will be shown in early August – days before Diana’s 20th anniversary on August 31.