One of France’s legendary public couples, Simone Signoret and Yves Montand, are about to be the subject of a nostalgia-soaked biopic that family members have disowned as a modernized travesty.

Moi qui t’aimais (I, who loved you) tells the story of the final years of the stormy 35-year marriage which fascinated the country from the 1950s to the 1980s.

Released to mark the 40th anniversary of Signoret’s death at 64, the tale of the politically active couple, friends of Jean-Paul Sartre, Pablo Picasso and Henry Miller, taps into enthusiasm for an era viewed by the younger generation as a golden age. The same vein is being mined by Renault cars with their best-seller, the retro-styled electric version of the 1970s R5.

Mixed reviews have greeted the film, in which Signoret, whose work included Les Diaboliques and Room at the Top, is played by Marina Foïs. Roschdy Zem plays Montand, a singer and actor known internationally for songs such as C’est Si Bon and movies such as Wages of Fear (1953) and Jean de Florette, made five years before his death in 1991.

Montand and Signoret in Les Sorcières de Salem, a 1957 French film based on Arthur Miller’s play The Crucible, with a screenplay by Jean-Paul Sartre.

The main criticism has been over the portrayal of Montand, whose serial infidelity, including a highly publicized affair with Marilyn Monroe, is not treated with the indulgence shown in his own era.

Outright hostility has come from the family, led by Benjamin Castaldi, 55, a television host who is Signoret’s grandson. He regards the film as feminist dogma that caricatures the grandmother and step-grandfather he knew as a boy. “This is a lazy fiction, built on deformed personalities and subjected to the ideological codes of our age,” he wrote in an open letter.

Influenced by the MeToo movement, “it turns Simone into an eternal silent victim and Montand into a smooth society predator”, he added. “That was not the real Montand. He was never this toxic male.”

Catherine Allégret, his actress mother, 79, disowned the film and said she had refused its makers the right to draw on Signoret’s successful 1976 autobiography Nostalgia Isn’t What It Used to Be.

Society predator and silent victim? Montand and Signoret in the 1950s.

Jean-Louis Livi, Montand’s nephew, said he refused to watch the movie, whose title is a line from one of Montand’s biggest songs, “Les Feuilles Mortes” (Autumn Leaves).

Diane Kurys, its director, who also made a 2008 biopic about Françoise Sagan, the postwar novelist, has hit back, denying any feminist distortion or that she portrayed Montand as “a bastard”. Castaldi “must have used ChatGPT to write that,” she added.

She had always been fascinated by the couple, two of the biggest ”monstres sacrés” of the postwar arts world, she said. “Theirs was an exceptional love story of three decades. They were public figures. They were a real legend and at the same time a real couple with their weaknesses, uncertainties and their betrayals,” she told Le Figaro newspaper.

Charles Bremner is the Paris correspondent at The Times of London