When JFK and Jackie visited Paris Jack the Zipper slipped away for a visit to one of Madame Claude's ladies, a Jackie lookalike.

In May 1961, an elderly woman in Paris heard a knock at the door of her six-story walk-up apartment. It was only the most powerful man in the world.

The president of the United States was going door-to-door hoping to find the call girl he had discreetly arranged to meet.

John F. Kennedy, it turned out, used a fake excuse about a doctor’s visit to attend a long-arranged dalliance while in Paris for a crucial summit, only to wind up in the wrong building, knocking on the doors of random Parisians who were left with the surprise of their lives.

Kennedy famously introduced himself as “the man who accompanied Jacqueline Kennedy to Paris.”

But while Jackie was thrilled at the prospect of meeting novelist and newly appointed French Culture Minister Andre Malraux, one of her literary idols, her husband looked to fulfill a different sort of fantasy.

“If JFK had a type, it was the wholesome, snooty, proper, preppy girl whose flaunted untouchability he could violate . . . girls like Jacqueline Bouvier,” writes Stadiem, who notes that Kennedy learned about Madame Claude from Sinatra.

“Here was a madam who specialized in exactly what JFK was after.”

The liaison, Stadiem writes, was arranged directly between Madame Claude and Pierre Salinger, Kennedy’s press secretary. When Salinger first proposed the arrangement, Claude turned him down, fearing the many things that could go wrong if the president’s visit to a prostitute went haywire.

But Salinger, the brains behind many of Kennedy’s most impactful speeches, convinced Claude that any problems could work in her favor — that a scandal would make her a legend to the sex-comfortable French, and that a successful dalliance would bring her to the attention of the world’s most powerful men.

“‘Rise to the occasion,’ Salinger exhorted Claude. ‘Do it for your career. Do it for your country,’ he riffed, paraphrasing JFK’s inaugural address. ‘Think big!’ ” Stadiem writes. “Weighing risks and rewards like the shrewd banker she might have otherwise been, Claude decided to go for it.”

Kennedy hoped to hook up with French actress and Jackie Kennedy-lookalike Anouk Aimée, who had just appeared in the Federico Fellini hit “La Dolce Vita.”

“What does he want her for? He’s already got her,” asked Claude, referring to Aimée’s resemblance to the president’s wife,

Stadiem writes. “He was drawn to Jackie’s looks but wanted a more seductive, sexual version.”

Aimée, however, was horrified at the suggestion, rejecting it outright — not for any reticence about a paid encounter, but because she considered Kennedy a “puerile warmonger.”

Claude found Kennedy a 23-year-old Sorbonne graduate who worked as a fitting model for Givenchy.

Salinger and Claude, aware of this, both thought that a Jackie lookalike adorned in a dress from the most French of designers would be like “waving a red cape at a bull; the bull was sure to charge, as was the president.”

For secrecy’s sake, it was determined that the dalliance would take place at the young woman’s apartment.