Gunilla von Post, the Swedish socialite, who had an affair with John F. Kennedy, died at 79.

Gunilla von Post was just 21 when she began seeing JFK, when he was 36 and Massachusetts senator.

JFK and Gunilla von Post affair began just a few weeks before his marriage to Jacqueline Bouvier and continued two years after their wedding.

Gunilla von Post went on to tell all in her memoir Love, Jack, which came out in 1997.

Swedish socialite and JFK met by chance in the French Riviera in August 1953.

Gunilla von Post had been sent there by her aristocrat father to brush up on her French.

John F. Kennedy was immediately blown away by her natural blonde beauty.

JFK and Gunilla von Post affair began just a few weeks before his marriage to Jacqueline Bouvier and continued two years after their wedding

The lovers spent one evening together in which, she recalled: “He turned and kissed me tenderly and my breath was taken away.

“The brightness of the moon and stars made his eyes appear bluer than the ocean beneath us.”

JFK admitted he was about to get married and sure enough, three weeks, on September 1 1953, he married Jacqueline Bouvier.

The love letters and trans-Atlantic phone calls soon followed and JFK told her he wanted to see her again.

John F. Kennedy visited Sweden with a friend in 1955 and the relationship was consummated in August 1955.

Gunilla von Post wrote: “I was relatively inexperienced, and Jack’s tenderness was a revelation. He said, <<Gunilla, we’ve waited two years for this. It seems almost too good to be true, and I want to make you happy>>.”

A week later they said their tearful goodbyes and a few painful months ensued.

According to Gunilla von Post, JFK called his father Joe to tell him he wanted to divorce Jackie and marry her.

JFK’s father said that would destroy his chances of reaching the White House.

He tried to get Gunilla von Post to move to New York and take up modelling but she said she would only do that if they were married.

It was a catch 22 situation which JFK ended with one last handwritten note in which he admitted his emotions were “complicated”.

According to Gunilla von Post, JFK called his father Joe to tell him he wanted to divorce Jackie and marry her

Gunilla von Post wrote of her short, sweet romance: “I borrowed him for a week, a beautiful week that no one can take away from me.”

Born on July 10, 1932, in Stockholm, her full name was Karin Adele Gunilla von Post.

Gunilla von Post went on to marry wealthy Swedish landowner Anders Ekman and three years later she had one final meeting with JFK.

Gunilla von Post and her husband were guests at a charity ball at the Waldorf Astoria, New York, which was also attended by JFK and Jacqueline Kennedy.

She scribbled a note on a napkin at her table and asked a waiter to pass it to the senator.

Moments later JFK signalled to meet him in a corridor.

Gunilla von Post wrote: “He just gave me a huge hug. And then he said <<It’s wonderful to see you. I love you>>.” She said “it was lovely”.

Gunilla von Post trained in hotel management and cookery and attended a finishing school in Lausanne.

JFK’s affairs, from Marilyn Monroe to the reputed girlfriend of a Mafia boss, have been well documented.

Those who doubted Gunilla von Post’s accounts were forced to eat their words last year when she decided to sell 11 of JFK’s handwritten letters and three telegrams on a Chicago online auction site.

The letters were all written after his marriage. In the first, sent five months after his marriage in March 1954, JFK asked: “Do you remember our dinner and evening together this summer at Antibes and Cagnes?”

In another letter JFK wrote: “I thought I might get a boat and sail around the Mediterranean for two weeks with you as crew. What do you think?”

Unfortunately for the lovelorn couple, JFK then sent a telegram cancelling it after suffering a back injury that needed surgery.

Those who doubted Gunilla von Post's accounts were forced to eat their words last year when she decided to sell 11 of JFK’s handwritten letters and three telegrams on a Chicago online auction site

The sale of the letters raised $115,537.50, beating the original estimate of $50,000.

Anders Ekman died in an accident, and Gunilla von Post later married Weisner Miller, an American IBM executive, and moved to America.

The second marriage ended in divorce, but Gunilla von Post continued to enjoy life on the international social circuit, supporting charities and moving between homes in Palm Beach, Sweden, the south of France and Switzerland.

Gunilla von Post is survived by two daughters of her first marriage and a son of her second.