Journalist and socialite; Born December 10, 1928; Died June 4, 2007. LADY Jeanne Campbell, who has died aged 78, was a journalist who reported for many years from New York City. Fittingly, her colourful life - numerous affairs with a string of political and cultural figures - would itself have been enough to sustain several columns of newspaper copy.

According to the US presidential speechwriter James C Humes, while in the United States she bedded John F Kennedy at her Georgetown house in October 1963; the Soviet leader Nikita Khruschev at his dacha in April 1964; and Cuban President Fidel Castro in Havana the following May. In this sense, she had much in common with her second stepmother, the notorious Margaret, Duchess of Argyll, who had a similarly voracious sexual appetite.

Her father, the reprobate 11th Duke of Argyll, divorced Margaret the year Campbell covered Kennedy's funeral, observing that Jackie Kennedy had "given the American people from this day on the one thing they always lacked - majesty". She later investigated various conspiracy theories that arose following the President's assassination.

Her parents' separation followed titillating divorce proceedings in which the duke produced photographs of the duchess wearing only her signature triple-string of pearls while fellating an unidentified man. His identity has never been revealed, although Margaret counted both the actor Douglas Fairbanks Jr and the defence minister Duncan Sandys among her lovers.

At the height of the proceedings, Campbell and her father broke into Margaret's London home to remove all her four-year diaries. The duchess attempted to call the police when they entered her bedroom, but the duke disabled her as his daughter swiped the pertinent volume. Margaret sued her stepdaughter for trespass and theft, later settling out of court.

Jeanne Louise Campbell was the only daughter of her father's first marriage to the Hon Janet Gladys Aitken, daughter of the Canadian press baron and politician Lord Beaverbrook. She was born in 1928 and her parents divorced seven years later, although she remained Beaverbrook's favourite grand-daughter.

Campbell endured a difficult relationship with her mother, who was a heavy drinker. It was said that when she was about four, Lord Beaverbrook asked her what he should do about her mother. "Cut off all her money, grandpa," she replied. He did not, but when his daughter married for a third time in 1942, she took her younger children (by her second marriage) to Canada after the war, leaving Jeanne behind.

After the war, Campbell trained as an actress, even joining the Old Vic, but in 1949 she became her grand-father's companion and travelled all over the world with him. She remained close to Beaverbrook despite his atrocious treatment of his mistresses, a cruel streak Campbell attributed to his Presbyterian upbringing.

By the early 1950s Campbell began a series of affairs rivalled only by her stepmother. In 1953 she came close to wedding William Ropner of the British shipbuilding family, but instead succumbed to the charms of Sir Oswald Mosley, the former Blackshirt leader, who pursued her chiefly in the hope of securing positive publicity via her grandfather.

Beaverbrook was furious, threatened to cut off her money and in the end dispatched her to New York City to write for the Evening Standard. She was not a natural journalist, but her status secured her access to the great and good if nothing else. She interviewed the oil baron J Paul Getty and wrote a critical article on the CIA, prompting her grandfather to caution sensitivity.

From 1959-61 Campbell had a passionate affair with Henry Luce II, founder and owner of Time-Life Inc, and the husband of the formidable Clare Booth Luce. He secured her a job at Life magazine and came close to leaving his wife for her, but in the spring of 1961 she met the writer Norman Mailer and soon fell pregnant.

Beaverbrook never took to Mailer and advised her to have his child (Kate) but not marry him. She did both, but the marriage was as disastrous as one of her father's and when Mailer strayed, she left, divorcing him in Mexico in 1963. His revenge was an unflattering portrayal of her in his novel An American Dream.

Beaverbrook died in 1964 and left his grand-daughter the income from a $500,000 trust. Jeannie married for a second time the same year. John Sergeant Cram was a gentleman farmer and great-great-grandson of the railway baron Jay Gould. They lived in New York and at Cram's plantation in South Carolina and, in 1967, Jeanne had a second daughter, Cusi Cram, although probably by another man, who - like Kate - became an actress.

Latterly, Campbell lived in a tiny flat in Greenwich Village, New York City, sleeping in Napoleon's old campaign bed. She is survived by both husbands and her daughters, Kate Mailer and Cusi Cram.