The film, Hilary and Jackie, will, like the siblings' biography A Genius In The Family, show family discord and du Pre seducing her brother-in- law.
In the movie Jacqueline makes plain that she wants Hilary's husband Christopher "Kiffer" Finzi in her bed. "I feel a million dollars this morning, that was exactly what the doctor ordered," she beams after Kiffer - played by David Morrissey - reluctantly obliges his demanding sister-in-law.
The film stars the Oscar-nominated actress Emily Watson as Jacqueline and is likely to reopen wounds between du Pre's family and friends. This time, though, the argument will be very public.
Next week Julian Lloyd Webber, the cellist and friend of du Pre, will denounce Jacqueline's siblings Hilary and Piers as driven by spite, and the film "a slur on Jackie's memory".
Jacqueline du Pre, with her flowing blond hair, good looks and vulnerability, was the golden girl of classical music in the sixties. Her recording of Elgar's Cello Concerto was widely praised and remains a touchstone for other versions.
At 28 she was diagnosed as having multiple sclerosis and stopped playing in public. When she died, at the age of 42, she became an icon in the classical music world and beyond. But in the book and film her sister Hilary, a gifted flautist (and originally thought to be the musical prodigy in the family), is shown as jealous and angry at being eclipsed by her sister's fame.
In turn, she paints Jackie as spoilt and manipulative, raging at those who care for her, and emotionally dangerous with overt designs on Christopher.
With the film certain to reach a much wider audience than the book, one of du Pre's most celebrated friends and admirers is about to break his silence on the controversy.
In the February issue of Classic FM Magazine, which goes on sale next week, Julian Lloyd Webber says: "She was the cellist I saw the most as a student. She left an impression of a radiant being who loved playing. This does not come over in Hilary and Piers's account. My main impression ... is that there's a spiteful streak in both Hilary and Piers, and these revelations are their ultimate act of spite and bitterness. It leaves me with a very unpleasant taste."
He adds: "People have to make their own way in life. I have a sibling who has been extremely successful, and I wouldn't entertain doing a book of this kind."
However, the classical music broadcaster Henry Kelly defends the film, which he has seen and describes as "very moving." He adds: "Jacqueline du Pre may have been selfish, rapacious with her sister's husband and a control freak who exploited her own perceived vulnerability.
"It makes her no less an artist ... At a time when her career should have been blossoming her health deteriorated, her husband Daniel Barenboim found a new love and life, and fathered a child.
"Jacqueline's world gradually fell apart. What unimaginable sadness this must have created within her."
Barenboim, du Pre's former husband, is refusing to comment. But Andrew Stewart of Classic FM Magazine has spoken to friends of the Israeli conductor, and those friends claim Barenboim is upset by both the book and the forthcoming film. There is even speculation that Barenboim might call on the French courts and France's tough privacy laws to halt its distribution across the Channel.
Carol Easton, a former du Pre biographer, suggested in her 1989 biography of the cellist that Jacqueline's relatives declined to support her as multiple sclerosis crippled her.
Hilary du Pre claims there was a reconciliation with her sister. But, as she slipped into her final coma, Jacqueline du Pre chose to be surrounded by her friends, not by her siblings.
Brother and sister stand to make money from the movie adaptation, which is directed by Arnand Tucker and, with Emily Watson, stars James Frain as Barenboim, Rachel Griffith as Hilary, Charles Dance as their father and Celia Imrie as their mother.
Hilary and Jackie has a gala charity premiere at the Barbican Centre on 20 January.
One critic who has seen a preview of the film says Emily Watson portrays du Pre with sensuality when she plays the cello, and is heartbreaking as her health fatally declines, while James Frain plays Barenboim as "a study in arrogance and bewilderment".
Hilary and Jackie marks the big-screen debut of Arnand Tucker, a documentary maker. He says the film is even-handed. "Hilary and Piers' story honestly moved me to the centre of my being.
"I had no idea of the price Jackie paid for her talent nor of the sacrifice that lay at the heart of Hilary's life.
"It touched something very deep in me ... Jackie's music has everything; love, hate, sadness, beauty, wonder. I think you belittle her and her music by trying to canonise her, by telling a lie about who she really was."
While Hilary and Jackie will cause pain to du Pre's friends, there is by contrast an amusing history to its title. It was originally going to be simply called Jackie. But American distributors foresaw confusion with Jackie Kennedy.
Now some fear that American audiences might believe they are going to see a film making comparisons between a first lady past and present.
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