Rupert Murdoch's wife Wendi Dengjaw: Dropping rumours to go with her looks

Wendi Deng, the continent-hopping, career-swapping, cream pie assailant-whacking wife of Rupert Murdoch, has proved only so adept at life on the big stage. Her talents are many, but ever since she married Rupert aboard his 155ft yacht 14 years ago, the odds have been stacked against her.

Murdoch, as everyone knows, is really married to his business, and although his third wife may have given him a new lease of life, two daughters and an assisted passage into the lucrative Chinese television market, there were many in the Murdoch cosmos who failed to take kindly to her.

"What first attracted you to your elderly billionaire husband?" was the question everybody joked about asking the young Chinese bride, a one-time waitress in a Los Angeles noodle parlour. The notion of Murdoch as a dynasty-devouring dragon-floozy proved hard to shift, and last week's news that Murdoch wants a divorce on the grounds of irretrievable breakdown was surprising only in its suggestion that, when you're 82, anything is retrievable. The couple's troubles - regular gossip in medialand for years - have recently seeped into the mainstream.

A year ago, the New York Times announced  Deng's "Declaration of Independence", reporting that the pair lived largely separate lives, and that Murdoch's corporate lieutenants were scheming to make sure that Murdoch "is kept at a distance". Happily, she was right by his side when, with one virtuoso display of marital devotion, she became an overnight global sensation. In 2011, Murdoch was giving stumbling evidence to a parliamentary committee investigating phone hacking, when a protester ran in from the wings and tried to splat him with a foam pie.

As others watched dumbfounded,  Deng launched herself at the attacker and landed a fearsome, karate-style right-hander with the sound of a halibut being dropped from a vast height on to a paving stone. The prankster, one Jonnie Marbles, said later: "I saw the rage in her eyes. It was scary. I wouldn't want a rematch." When you are as rich as Murdoch, divorce is a costly and complex prospect.

His previous wife, Anna, collected $1 billion when he divorced her in 1999, 17 days before marrying the then 30-year-old Deng. It is unlikely that she will receive much less. Some Murdoch-watchers expressed surprise that the couple hadn't settled for a simpler together-but-apart arrangement. By taking the heavy option, Murdoch has fed the notion that something irresolvable has happened in the background.

This was given a dose of rocket fuel by the BBC's business editor, Robert Peston, who claimed in a tweet that "the undisclosed reasons for Murdoch divorcing Deng are jaw-dropping". Allegations of Deng's indiscretions have flown around for years, sometimes in such profusion and detail as to suggest a deliberate smear campaign.

American newspapers have, from time to time, been contacted by an anonymous tipster using the Gotham City pseudonym Harvey Dent to identify supposed lovers from the worlds of politics, big business or the movies.

The greater likelihood that Deng was never really cut out for life as a Murdoch, and that as her husband has aged and his power has flowed in the direction of others - particularly his grown-up children by Anna - so things have become more difficult for his outsider wife. The couple met in 1997 at a time when Murdoch was trying, with uncharacteristic lack of success, to break into the Chinese media market.

The story goes that Murdoch was berating the troops at his Hong Kong TV headquarters when Deng, a junior employee, stood up and asked: "Well, why is your China strategy so bad?" He sought her out afterwards and was struck, not only by her confidence, but by what Vogue magazine called "the kind of looks usually reserved for a James Bond villainess".

Soon, she was not only his wife, but a key tool in his advance upon China. Deng was born in eastern China in 1968, one of four children. "I grew up in a funny little town called Xuzhou," she has said. "In the countryside, very poor. We didn't have hot water." Her parents were factory engineers and convinced Communist Party members, who named her Wenge meaning "cultural revolution".

She later changed it to Wendi, but praises her mother and father for pushing her towards learning and achievement and ultimately into a medical school in Guangzhou, close to the Hong Kong border. It was there that she met an American woman, Joyce Cherry, who taught her English and became a friend.

When Cherry and her husband, Jake, returned to the US, they obtained permission for Ms Deng to accompany them and to continue her studies at California State University. Not long after arriving in Los Angeles, however, Cherry discovered that Jake and the teenage Wendi were having an affair. The Cherrys divorced. Deng and Jake married. By the time it ended, just four months later, Deng had decided to stay in the US. She worked punishing hours in a Chinese restaurant to support her studies, landing a prized place at Yale Business School, and later a job at Murdoch's Star TV subsidiary.

She was on a trip to drum up business in Hong Kong when the boss breezed through. If  Deng's rise rings with a certain ruthlessness, her supporters insist it is not the whole story. Many claim that her influence on Rupert has been overwhelmingly good.

"She is fabulous to work with, a real pro, terrific at bringing people together," said Tina Brown, the magazine editor. The girl from Guangzhou has the glamour, the money and the connections, but her future seems less certain. If life as Murdoch isn't always easy, it can be a lot harder when you are suddenly someone else.