Sean Smith - Kim Kardashian

His confession didn’t harm their marriage. In some ways, his revelation brought them closer together, as sharing a secret sometimes can. In her eyes, he remained a real guy, who was, quite simply, her hero.

After graduation, the couple moved to California, where the training facilities and the climate were better suited to an athlete with his eye on Olympic gold. Chrystie worked as an air hostess for United Airlines to support them, because in those days the Olympics were strictly for amateurs. She was entitled to free plane tickets, which were a godsend for Bruce, as it gave him the means to travel to athletics meetings all over the world. Today sport is a professional career and Bruce Jenner, an all-American hero, would have been a multi-millionaire, travelling first class around the world.

Chrystie was by his side when he flew to Montreal for the 1976 Olympics. He was the current world record holder and favourite to win. He was in second place after day one, but came charging through to claim the gold. He embraced his young wife, wrapped himself in the American flag and, for a fleeting moment, was the most famous man in the world. Now he needed to make some money.

Frank Litsky of the New York Times famously wrote of his triumph: ‘Bruce Jenner of San Jose, California, wants to be a movie or television star. After his record-breaking victory in the Olympic decathlon, he probably can be anything he wants.’ He wanted to be a woman and that was one thing he couldn’t be … then. Instead, he immediately retired from athletics.

Just when it seemed nothing could interrupt a happy future, tragedy struck the Jenner family. His younger brother Burt died in a car crash. Bruce was visiting his parents’ home in Connecticut and during his stay was loaned a Porsche by a local car dealer. Eighteen-year-old Burt volunteered to fill her up with petrol, but ended up crashing into a telegraph pole. He died in hospital, along with his young girlfriend, who had skipped school to go for a ride in the top-of-the-range sports car.

Bruce named his first child Burt in honour of his much-loved brother. His son was born in 1978, six years after he and Chrystie were married. Sadly, the cracks had already begun to appear in their relationship. Faced with a future that did not contain eight hours of athletics practice a day, the reality of Bruce’s gender dysphoria – the technical term for his gender identity crisis – was making him unhappy and discontented with his situation.

He and Chrystie separated for the first time the following year, and he met the woman who would eventually become his second wife at a celebrity tennis tournament. It was held at the Playboy Mansion in upmarket Holmby Hills, LA, where he had been staying temporarily. Bruce won the tournament and the beautiful Linda Thompson presented him with the trophy.

She provided another bizarre link with Elvis Presley in the Kardashian family saga. His relationship with her was probably the most important Elvis had after Priscilla. She was a 5ft 9in willowy blonde, who was the reigning Miss Tennessee when she met The King. He moved her into Graceland, his famous mansion near Memphis, in 1972, and she was with him for four years.

Linda had been a speech and drama major at MSU (Memphis State University) and, by all accounts, was the brightest of Elvis’s women. She was popular with the notorious Memphis Mafia – the entourage who seemed to be ever present with Elvis – and she had looked after him well. Marty Lacker, the unofficial foreman of the group, explained, ‘She was like a mother, a sister, a wife, a lover, and a nurse.’

Elvis had bought an apartment for her in Santa Monica so she could pursue her acting ambitions. After he died in 1977, she became a regular member of the cast of a variety show called Hee Haw as a singer of country music.

Bruce was immediately struck by Linda’s statuesque presence. He told her he and Chrystie were separated and they hit it off right away. He was uncertain about his future, however, and briefly reconciled with his wife. After Chrystie fell pregnant, he wanted her to have an abortion, because their marriage had failed. He told Playboy magazine in July 1980, one month after the birth, ‘My first reaction was that I didn’t want it.’

Initially, Chrystie went along with his wishes, and even paid for an abortion, but changed her mind after a conversation with a friend made her realise she didn’t want to go through with the termination. She said at the time, ‘I thought, “What an idiot I am.” I wanted the baby very, very much. But I was conditioned to make decisions that were best for him [Bruce]. It was totally my choice to have the baby.’

Bruce now says he too rejected the idea of an abortion, but when Cassandra, his eldest daughter, was born, he was in the middle of divorce proceedings and sitting in a hotel room far away in Kansas City. In his famous ground-breaking interview with Vanity Fair in July 2015, he told Buzz Bissinger that he wasn’t present at the birth: ‘Under the circumstances I could not even see myself being there.’

Instead, he resumed his relationship with Linda. They married soon afterwards, in January 1981, in a beautiful setting overlooking the Pacific Ocean in Hawaii at the beachfront house of Allan Carr, the producer of Can’t Stop the Music . Bruce’s son Burt was best man, even though he was only two, and spent the entire ceremony tugging at his father’s sleeve, saying, ‘I want up.’ Linda walked down the ‘aisle’ to the sound of Elvis singing ‘Hawaiian Wedding Song’. It was very romantic.

At the time, Linda was already three months pregnant with their first child, Brandon, who was born the following June. Fortunately, she got on well with Bruce’s older children, both of whom came to the hospital to visit their new brother.

Linda and Bruce became fixtures on the celebrity circuit around Los Angeles, making friends with stars like Michael Jackson, Lionel Richie and Sugar Ray Leonard, who would later feature in the Kardashian story. They appeared on the front cover of Playgirl magazine in May 1982: she revealed an impressive cleavage; he showed a lot of chest hair.

The cover headline on the article read ‘The Fall and Rise of an American Hero’. This bolstered the Bruce Jenner image of a man fighting against the disadvantages of life, including dyslexia. His story was one of triumph over adversity and was a considerable money-spinner during his years as a media personality and motivational speaker. It was an image he later promoted in his 1996 book Finding the Champion Within .

At no stage did he reveal to his audience his real struggle within. He would bounce on stage, all vigour and enthusiasm, wearing a pair of silk panties underneath his three-piece suit. Bruce, it appeared, was a master of living up to an image created for the general public. It wasn’t real.

The offers flooded in after the Olympics and soon Bruce was a very wealthy young man. He appeared on all the top talk shows, including The Tonight Show starring Johnny Carson and The Merv Griffin Show . He became a well-known face on sports programmes, at one time co-presenting the popular Wide World of Sports .

He also revealed an entrepreneurial streak that would later fit in very well with the Kardashian flair for business. Their philosophy is all about making the most of every opportunity. Bruce bought his first plane in 1978 and started Bruce Jenner Aviation, which sells aircraft supplies.

He was marketed as a personality much more than the usual famous sportsman. He became the spokesperson and face on the packet of the iconic cereal Wheaties, the ‘breakfast of champions’, and a million families breakfasted with Bruce on the kitchen counter every day for years.