The cruel way Wallis Simpson 'repaid' Edward VIII after he tossed away his crown and reign... all so he could be with her: How American socialite CHEATED and even carried on the the 'toy boy' affair when he confronted her

He tossed away his crown and an empire for 'the woman I love' - and she repaid him by having a fling with a playboy young enough to be her son.

The legend of King Edward VIII and his abdication has filled a thousand books and inspired countless films, TV documentaries and stage plays. But the story of how Wallis Simpson cheated on Britain's king remains – even seventy years on – something few people know about.

Edward fled the throne in December 1936. He married double-divorcee Wallis the following year, and as their lives slid from majestic grandeur into a welter of glittering parties, cocktails and photo calls, they became the world's first media superstars.

Again and again, their romance was labelled the greatest love story ever told. But the truth was somewhat different.

By 1950, thirteen years after they wed, Edward – now 56 - and Wallis, 54, had been everywhere, done everything, met everybody. The Duchess of Windsor was bored beyond endurance.

“You don't know how hard it is to live out a great romance,” she snapped when a friend asked her how things were going.

But all that was to change when the Windsors boarded the liner Queen Mary in New York, bound for France, on May 24 1950.

Also on the passenger-list was Jimmy Donahue, 34, grandson of the legendary Frank Woolworth – whose five-and-dime stores were in every town and city centre throughout Britain and the United States.

Jimmy had no fortune of his own but his mother Jessie Donahue was wealthy - and was ready to give him whatever he wanted. He never had to do a day's work in his life, So he made a job out of wicked pranks and tricks.

He was slim, dazzlingly attractive and gay. But Jimmy loved the company of women and he knew how to make them laugh.

On that voyage to France he made Wallis laugh. And then, as he measured his success, the prankster in him took over. He started romancing her, despite the fact she was nearly 20 years older and one of the most famous women in the world. And despite the fact he was homosexual.

In Paris, he bought her jewels and sent her flowers. The duke, seeing how flamboyantly gay Jimmy was, never for one second thought the boy could present a threat to his marriage and, bankrolled by the Woolworth millions, the Windsors and Jimmy became a threesome fixture on the nightclub circuit of the French capital.

'The duchess became infatuated with him', the duke's godson David Metcalfe told me. 'He had control of her. She couldn't do without him.'

Did they have sex? Mona Eldridge, secretary to Jimmy's cousin Barbara 'Poor Little Rich Girl' Hutton, says yes.

'I know it was physical,' she added. 'There was sexual activity. She was besotted by him, she chased him. She really fell for him.' In the history of love, it was the greatest betrayal of all.

Apart from this unexpected sexual re-awakening, the affair's allure, for the duchess, was its clandestine nature – she became skittish at the prospect of secret night-time adventures.

Billy Livingston, Jimmy's lifetime friend, reported finding Wallis hiding on the floor of a limousine as she went off on a date with Jimmy. 'She enjoyed all the wildness and the things they did,' he recalled.

But the duke finally twigged what was going on. In an emotional showdown witnessed by his private secretary, the ex-king called his wife out. He pleaded with her to give him up. She refused.

The scene took place in the Waldorf Towers in New York, where the Windsors kept a private suite, in 1953. 

According to a note written by Anne Seagrim, the duke's private secretary: ‘The day that he came back from the Racquets Club – where someone had told him “in his own interests” that the Duchess had been out every night till dawn with the same young man – he went to his room and lay on his bed. She came in and, gaily unknowing, and went into his room.

‘I heard him choking back the tears in his voice, telling her what he had heard. I heard him say what he had no doubt rehearsed over and over again – “It’s not because you are the Duchess of Windsor, it’s because you are my wife. Any man would mind his wife doing this.”

‘His voice wavered. She never said a single word – or at any rate I didn’t hear her voice, and very soon she came out, all her gaiety gone – walking slowly with her head bent, her face submissive, her eyes blue & bewildered. She gave me a quick glance as she went through my room.

‘She was very quiet and submissive for a long time afterwards. She telephoned immediately cancelling whatever arrangement she had made with the young man.’

But the affair continued. And, Ms Seagrim says damningly of the duchess: ‘She revelled in this shoddy little success.’ Jimmy gained in boldness. He proposed marriage to Wallis.

And she, American-born and all too conscious of the colossal Woolworth fortune – far greater than that of her husband – faltered for a moment before realising the futility of it all.

Then adversity struck. On a tour of Austria with the duke and duchess, and probably drunk, Jimmy kicked her on the shin under the dinner table. Her leg started to bleed.

The duke jumped up in anger. 'We've had enough of you, Jimmy,' he shouted. 'Get out!'

And that was that – after four years and three months, Wallis's autumn fling was over. A friend bumped into Jimmy in New York soon after and asked him how the duchess was. 'Haven't you heard?”' he replied. 'I've abdicated!'

• CHRISTOPHER WILSON is the author of Dancing With The Devil – the Windsors and Jimmy Donahue (HarperCollins).