Married to the most controversial British politician of the last century, Lady Diana Mosley was a friend of both Winston Churchill and Adolf Hitler.

Nick Morrison looks at the turbulent life of the greatest society beauty of her age.

ADOLF Hitler was a guest at her wedding, held in the drawing room of Nazi propaganda minister Joseph Goebbels. But while to the Fuhrer she was "an angel", to MI5 she was the most dangerous woman in Britain, reviled and hated by the society she once graced.

It had all started so promisingly for Lady Diana Mosley, who has died at the age of 93. Born into one of the most celebrated aristocratic families, privileged by both her beauty and wealth, she seemed destined to be one of the most dazzling among her already glittering set. A friend of Winston Churchill, she counted sculptor Augustus John and writer Evelyn Waugh among her social circle, her position only enhanced by a glamorous first marriage.

But her love for, and marriage to, Sir Oswald Mosley, founder of the British Union of Fascists and one-time Prime Minister-in-waiting if Britain were to fall to the Nazis, provided the defining thread of her life, turning the society beauty into a pariah.

Even after the war, with the Nazis defeated and her reputation seemingly beyond rehabilitation, she remained unrepentant, refusing to either renounce her past or condemn the dictator whose dark blue eyes captivated her. "They will go on persecuting me until I say Hitler was ghastly," she once said. "Well, what's the point of saying that? We all know he was a monster, that he was cruel and did terrible things. But that doesn't alter the fact that he was obviously an interesting figure," adding in a later interview, "I was very fond of him. Very, very fond."

Diana was the third and reportedly the most beautiful of the six Mitford sisters, a family immortalised by her sister Nancy in her novel, Love in a Cold Climate. As a girl, she used to stay with the Churchills at their family home of Chartwell, and she was a cousin of Clementine Churchill, the Prime Minister's wife.

When she was 18, she married Bryan Guinness, a charming, handsome and incredibly rich young man, but three years later she met Sir Oswald Mosley, a high-flying former Labour MP who had abandoned the party as the tidal waves of the Wall Street Crash swamped Britain's economy.

At the time of their meeting, Mosley was head of his own New Party and one of the most prominent politicians in the country, but already moving towards fascism. Eight months later he was to set up the British Union of Fascists, as the economic crisis provided him with a rich seam of converts.

Although Mosley was married, the two became lovers. Diana began divorce proceedings and moved into a house around the corner from Mosley's London flat, while his wife, Lady Cynthia Mosley, could only look on helplessly. When Cynthia died the following year, her family believed her husband's affair with Diana had sapped her will to live.

As well as freeing Mosley for marriage, 1933 saw Diana visit Germany with her younger sister Unity, who was becoming increasingly obsessed with fascism. Unity, who was to become so besotted with Hitler that she shot herself on the outbreak of war, introduced her sister to the Fuhrer.

A tall blonde, Diana represented the Aryan ideal and captivated Hitler, and his admiration was reciprocated. Diana said of their meeting: "His eyes were dark blue, his skin was fair and his brown hair exceptionally fine. In certain moods he could be very funny. He was extremely polite towards women."

The following year, two days after Mosley's Blackshirts had been turned back at the Battle of Cable Street in the East End of London, Diana and Mosley married. By then their notoriety was so great, the only place where they could be free from prying newspapermen was Nazi Germany, protected by Hitler's control of the Press. After their Berlin wedding, the Fuhrer presented the couple with a picture of himself in an eagle-topped silver frame.

Diana continued to visit Hitler as Britain and Germany moved ever closer to war, and in August 1939 she was a guest of the Fuhrer at the Bayreuth Festival, where he apparently told her that conflict was inevitable. The following month, war broke out.

As the first few months started to go badly for Britain, the government introduced an emergency measure to detain enemy aliens and suspect figures. The next day, Mosley was arrested and taken to Brixton Prison. A month later, Diana - then breastfeeding her 11-month-old son Max, now head of the Federation Internationale de l'Automobile and business partner of Formula One boss Bernie Ecclestone - was also arrested and taken to Holloway Prison.

Although she had never become involved in politics directly, her frequent visits to Germany and links with Hitler condemned her. An MI5 file, released last year, revealed that she was considered a greater threat than her husband. One report read: "Diana Mosley is reported on the best authority, that of her family and intimate circle, to be a public danger at the present time. Is said to be far cleverer and more dangerous than her husband and will stick at nothing to achieve her ambitions. She is wildly ambitious."

Even in the midst of her privations, and separated from her children, she refused to compromise her beliefs. Interviewed by the Home Office, she said she would like the British political system replaced with the German one, "because we think it has done well for that country". Asked if she approved of the Nazi treatment of Jews, she replied: "I am not fond of Jews".

Despite her indefatigable spirit, she was still able to call on the favours of family friends. By Christmas, Churchill had agreed to allow Mosley to become Holloway's first-ever male inmate, so the couple could be together.

After three-and-a-half years in prison, Diana and her husband were released in November 1943, on the grounds of Mosley's ill health, and were kept under house arrest for the rest of the war. Six years later, they moved to France, where Mosley continued to write and publish leaflets, as well as give lectures. They became friends with the Duke and Duchess of Windsor, and in 1980 Diana published a book on the Duchess.

While Mosley, who died in 1980, came to rue his friendship with Hitler, calling him a "terrible little man", Diana had no such conversion. "He was an extraordinary and remarkable man, and I shall never regret knowing him," she said, although she did come to recognise the extent of his evil, saying: "What happened in the war, the killings in the camps and so on, was something unimaginable to me. I didn't believe it for quite a long time. Then in the end I had to. It was a great crime."

This belated recognition of the truth of Hitler's regime did little to restore Diana's reputation, although she remained blithely unconcerned by the opinion of others.

Her last years in a Paris apartment, spending her days reading and entertaining, may have given little clue to the threat she once posed, but her death draws a curtain over the last link to Britain's flirtation with fascism.