In the 1960s and 1970s, when the Trente Glorieuses, France’s post-war boom years, were at their height, “Madame Claude” was part of the Parisian establishment, supplying high-class prostitutes to politicians, businessmen and foreign leaders from John F Kennedy to the Shah of Iran — and reporting on them to the French secret police.

Her multimillion-dollar empire disintegrated, however, after she fell foul of President Valéry Giscard d’Estaing in what some saw as a decision to destroy the threat she posed to the powerful.

Now the story of Madame Claude — real name Fernande Grudet — is being brought to a post-MeToo generation in a biopic. Its director, Sylvie Verheyde, portrays her anti-heroine as an ambiguous mixture of successful businesswoman and “female thug” — and something of a feminist icon.

On the set of Madame Claude.

Verheyde, 52, has been fascinated by the story since growing up in the 1980s when her mother held up Grudet as a role model. “Despite the fact she made her money as a madam, she was someone who came from a modest background and succeeded in having power alone — without the help of a man,” Verheyde said in an interview last week.

The director also found she had an indirect connection to her subject: among her friends are several former “testeurs” — young men asked by Claude to rate her newly trained prostitutes before they were sent out to paying clients.

Her multimillion-dollar empire disintegrated, however, after she fell foul of President Valéry Giscard d’Estaing in what some saw as a decision to destroy the threat she posed to the powerful.

In the film, Madame Claude, Verheyde tackles the mythology that has grown up around Grudet, which was fueled in large part by a celebratory film of the same name made in 1977 by Just Jaeckin, the director of Emmanuelle. He collaborated closely with Grudet on the project — so closely she even sent him round one of her “swans”, as she called her women. “The film was just part of marketing for her,” Verheyde said.

Grudet’s success lay in her embrace of the humble telephone. Rather than visiting brothels or picking up prostitutes on the streets, a client had only to call and a woman would be sent round to his apartment or hotel room. The concept of the call girl was born.

“She was the first person to understand how the telephone could transform things,” Verheyde said. “She was a genius in her line of business, just as Pablo Escobar [the Colombian drug lord] was a genius in his.”

Grudet (Madame Claude), in 1986, when she was on trial in France.

Grudet, a former street prostitute, put great care into choosing her women, who accompanied clients to chic clubs and expensive restaurants as well as to bed. Typically aged 25 to 30, they were usually tall and slender and often models, singers or actresses. A few older married women in search of adventure were also among them.

The “swans” were checked out regularly for venereal diseases. And if Grudet did not think their features were up to scratch — she usually didn’t — she sent them to the same cosmetic surgeon she had often used herself. If they left her employment they would have to refund the cost of the plastic surgery.

A client had only to call and a woman would be sent round to his apartment or hotel room. The concept of the call girl was born.

Grudet gave them basic English lessons and a crash course in culture — or at the very least a few magazine subscriptions. “She provided them with a kind of cultural veneer,” Verheyde said. “Everything was done to make it seem like they came from the same world as their clients.

“They were well paid and well treated, but it was still prostitution. These were girls in their twenties who found themselves in situations where they were necessarily faced with abuse or violence.”

Grudet was born in 1923 into a poor family in Angers and became a single mother at 16. Verheyde is fascinated by how she fooled the Paris establishment into thinking she was one of them.

“Her entire strategy was based on lying,” Verheyde said. “She said she was middle class and came from a good background, that she had been educated in a convent and had been in the Resistance.”

Even more outrageously, Grudet claimed to have spent time in Ravensbrück, the Nazi concentration camp for women. “She invented a character for herself that was very interesting to deconstruct, to solve the riddle of who she really was.”

Françoise Fabian, Klaus Kinski, and Murray Head on the set of The French Woman, a 1977 film based on the life of Madame Claude.

Grudet’s pretense succeeded: in a pre-Internet world it was difficult for doubters to check out her story. At one stage she had as many as 400 women on her books. She also worked with French intelligence services, sharing with them the contents of the little black book she kept on her clients. Sometimes they paid her to send her women on missions. In return she was given official protection.

It all went wrong after Giscard d’Estaing came to power in 1974. While his own love life was wreathed in rumor and mystique — virtually de rigueur for French presidents of that era — his administration clamped down on high-end prostitution. Previously practicing discretion, Grudet had become too well known, talking to journalists and writing a book. “She became an embarrassment for the authorities,” Verheyde said.

Grudet fled to America and set up home in some style in California, but, although she got back into the business, supplying women for Frank Sinatra and Sammy Davies Jr, she never really established herself. She even had a brief stint running a bakery — an odd career choice for a woman who had once declared: “There are two things that people will always pay for: food and sex. I wasn’t any good at cooking.”

After Giscard d’Estaing was ousted in 1981 by François Mitterrand, Grudet thought the coast was clear and returned to France where she was briefly jailed for tax evasion before resuming her old trade. Then in the 1990s authorities finally prosecuted her for proxénétisme (procuring). She died in 2015 in Nice, aged 92, alone and largely forgotten. Only six people attended her funeral.

The film is ready for release, although its distributors have yet to fix a date. Most French cinemas are open, despite the pandemic, but attendance is poor. “We are waiting for the right moment,” Verheyde said.

Peter Conradi co-authored The King’s Speech: How One Man Saved the British Monarchy