Rosa Monckton will tell the broadcaster that use of the Diana strips, disclosing dialogues entered by the Princess of Waless speech coach, is outrageous

One of Princess Dianas closest friends is writing to Channel 4 bosses asking them to scrap a forthcoming documentary using private video footage which includes Diana talking about about her fornication life with Prince Charles.

Rosa Monckton, a confidante of Dianas until she was killed in a Paris car crash 20 years ago next month, will argue that the confessional videos that Diana made as part of a course of speech coaching amounted to therapy and that using them is an intrusion and resentment that betrays Dianas right to privacy.

The documentary is due to be broadcast on Sunday 6 August and Moncktons intervention will increase pressure on Channel 4 after Dianas brother, Earl Spencer, reportedly required the programme was descent. Spencer is believed to have complained the documentary would hurt Dianas sons, Prince William and Prince Harry. The broadcaster confirms that it is currently in correspondence with Spencer but organized a defence of the programme claiming sound recordings, while constructed in private, were an important historical informant. The sovereigns have declined to comment.

This doesnt belong in the public domain, Monckton told the Guardian. It is a sellout of her privacy and of the familys privacy. I certainly dont think they should be program. The[ tapes] “mustve been” dispatched to the young princes.

The key root fabric for the film, Diana: In Her Own Words, comes from tapes the princess acquired in 1993 with her public-speaking tutor Peter Settelen as she talked about her life, ostensibly to help her improve her speeches on issues such as landmines and HIV and Aids. The tapes include her saying that fornication with Charles happened formerly every three weeks and that aged 24 and already married, she fell deeply in love with an unnamed member of the royal household, widely thought to have been the close protection officer Barry Mannakee, who later died in a motorcycle coincidence. She recalled that in 1979, two years before their marry Charles chatted me up. He was like a bad rash.

She contributed: He was all over me and I conceived, you are familiar with, Urgh. Whereupon he leapt upon me and started kissing me and everything, and I envisioned, Waaah! This is not what beings do.

She too talked about the engagement interview with Charles in which he was asked whether he was in love and reacted whatever in love entails. She recalled to Settelen that she had said yes, she was in love, like the fatty Sloane Ranger that I was.

The frank documentary is understood to have led to headache in palace cliques over whether it is a consequence, at least in part, of Prince William and Prince Harrys strategy of speaking out emotionally and in highly personal expressions in the run up to the 20 th commemoration of their moms extinction. The lords cooperated with both the BBC and ITV on recent documentaries and made a series of emotional statements about their agony. It recognized a retirement from the usual imperial protocol of carefully guarding private the questions and contrasted with their decision not to say anything about their private impressions on the 10 th anniversary of her demise in 2007, when they staged a pop concert at Wembley stadium in their moms memory.