But there is another Mrs McCain who casts a ghostly shadow over the Senator’s presidential campaign. She is seldom seen and rarely written about, despite being mother to McCain’s three eldest children.

And yet, had events turned out differently, it would be she, rather than Cindy, who would be vying to be First Lady. She is McCain’s first wife, Carol, who was a famous beauty and a successful swimwear model when they married in 1965.
She was the woman McCain dreamed of during his long incarceration and torture in Vietnam’s infamous ‘Hanoi Hilton’ prison and the woman who faithfully stayed at home looking after the children and waiting anxiously for news.
But when McCain returned to America in 1973 to a fanfare of publicity and a handshake from Richard Nixon, he discovered his wife had been disfigured in a terrible car crash three years earlier. Her car had skidded on icy roads into a telegraph pole on Christmas Eve, 1969. Her pelvis and one arm were shattered by the impact and she suffered massive internal injuries.
When Carol was discharged from hospital after six months of life-saving surgery, the prognosis was bleak. In order to save her legs, surgeons
had been forced to cut away huge sections of shattered bone, taking with it her tall, willowy figure. She was confined to a wheelchair and was forced to use a catheter.

Through sheer hard work, Carol learned to walk again. But when John McCain came home from Vietnam, she had gained a lot of weight and bore little resemblance to her old self.

Today, she stands at just 5ft4in and still walks awkwardly, with a pronounced limp. Her body is held together by screws and metal plates and, at 70, her face is worn by wrinkles that speak of decades of silent suffering.
For nearly 30 years, Carol has maintained a dignified silence about the accident, McCain and their divorce. But last week at the bungalow where she now lives at Virginia Beach, a faded seaside resort 200 miles south of Washington, she told The Mail on Sunday how McCain divorced her in 1980 and married Cindy, 18 years his junior and the heir to an Arizona brewing fortune, just one month later.

Carol insists she remains on good terms with her ex-husband, who agreed as part of their divorce settlement to pay her medical costs for life. ‘I have no bitterness,’ she says. ‘My accident is well recorded. I had 23 operations, I am five inches shorter than I used to be and I was in hospital for six months. It was just awful, but it wasn’t the reason for my divorce.

‘My marriage ended because John McCain didn’t want to be 40, he wanted to be 25. You know that happens...it just does.’

Some of McCain’s acquaintances are less forgiving, however. They portray the politician as a self-centred womaniser who effectively abandoned his crippled wife to ‘play the field’. They accuse him of finally settling on Cindy, a former rodeo beauty queen, for financial reasons.
McCain was then earning little more than £25,000 a year as a naval officer, while his new father-in-law, Jim Hensley, was a multi-millionaire who had impeccable political connections.

He first met Carol in the Fifties while he was at the US Naval Academy in Annapolis. He was a privileged, but rebellious scion of one of America’s most distinguished military dynasties – his father and grandfather were both admirals.
But setting out to have a good time, the young McCain hung out with a group of young officers who called themselves the ‘Bad Bunch’.

His primary interest was women and his conquests ranged from a knife-wielding floozy nicknamed ‘Marie, the Flame of Florida’ to a tobacco heiress.

Carol fell into his fast-living world by accident. She escaped a poor upbringing in Philadelphia to become a successful model, married an Annapolis classmate of McCain’s and had two children – Douglas and Andrew – before renewing what one acquaintance calls ‘an old flirtation’ with McCain.

It seems clear she was bowled over by McCain’s attention at a time when he was becoming bored with his playboy lifestyle.

‘He was 28 and ready to settle down and he loved Carol’s children,’ recalled another Annapolis graduate, Robert Timberg, who wrote The Nightingale’s Song, a bestselling biography of McCain and four other graduates of the academy.
The couple married and McCain adopted Carol’s sons.

It was in 1969 that Carol went to spend the Christmas holiday – her third without McCain – at her parents’ home. After dinner, she left to drop off some presents at a friend’s house.

It wasn’t until some hours later that she was discovered, alone and in terrible pain, next to the wreckage of her car. She had been hurled through the windscreen.

After her first series of life-saving operations, Carol was told she may never walk again, but when doctors said they would try to get word to McCain about her injuries, she refused, insisting: ‘He’s got enough problems, I don’t want to tell him.’

H. Ross Perot, a billionaire Texas businessman, future presidential candidate and advocate of prisoners of war, paid for her medical care.
When McCain – his hair turned prematurely white and his body reduced to little more than a skeleton – was released in March 1973, he told reporters he was overjoyed to see Carol again.
But friends say privately he was ‘appalled’ by the change in her appearance. At first, though, he was kind, assuring her: ‘I don’t look so good myself. It’s fine.’
He bought her a bungalow near the sea in Florida and another former PoW helped him to build a railing so she could pull herself over the dunes to the water.
‘I thought, of course, we would live happily ever after,’ says Carol. But as a war hero, McCain was moving in ever-more elevated circles.

Through Ross Perot, he met Ronald Reagan, then Governor of California. A sympathetic Nancy Reagan took Carol under her wing.
But already the McCains’ marriage had begun to fray. ‘John started carousing and running around with women,’ said Robert Timberg.

McCain has acknowledged that he had girlfriends during this time, without going into details. Some friends blame his dissatisfaction with Carol, but others give some credence to her theory of a mid-life crisis.
He was also fiercely ambitious, but it was clear he would never become an admiral like his illustrious father and grandfather and his thoughts were turning to politics.

In 1979 – while still married to Carol – he met Cindy at a cocktail party in Hawaii. Over the next six months he pursued her, flying around the country to see her. Then he began to push to end his marriage.
Carol and her children were devastated. ‘It was a complete surprise,’ says Nancy Reynolds, a former Reagan aide.

‘They never displayed any difficulties between themselves. I know the Reagans were quite shocked because they loved and respected both Carol and John.’
Another friend added: ‘Carol didn’t fight him. She felt her infirmity made her an impediment to him. She justified his actions because of all he had gone through. She used to say, “He just wants to make up for lost time.”’

Indeed, to many in their circle the saddest part of the break-up was Carol’s decision to resign herself to losing a man she says she still adores.

Friends confirm she has remained friends with McCain and backed him in all his campaigns. ‘He was very generous to her in the divorce but of course he could afford to be, since he was marrying Cindy,’ one observed.

McCain transferred the Florida beach house to Carol and gave her the right to live in their jointly-owned townhouse in the Washington suburb of Alexandria. He also agreed to pay her alimony and child support.

A former neighbour says she subsequently sold up in Florida and Washington and moved in 2003 to Virginia Beach. He said: ‘My impression was that she found the new place easier to manage as she still has some difficulties walking.’
Meanwhile McCain moved to Arizona with his new bride immediately after their 1980 marriage. There, his new father-in-law gave him a job and introduced him to local businessmen and political powerbrokers who would smooth his passage to Washington via the House of Representatives and Senate.

And yet despite his popularity as a politician, there are those who won’t forget his treatment of his first wife.

Ted Sampley, who fought with US Special Forces in Vietnam and is now a leading campaigner for veterans’ rights, said: ‘I have been following John McCain’s career for nearly 20 years. I know him personally. There is something wrong with this guy and let me tell you what it is – deceit.

‘When he came home and saw that Carol was not the beauty he left behind, he started running around on her almost right away. Everybody around him knew it.
‘Eventually he met Cindy and she was young and beautiful and very wealthy. At that point McCain just dumped Carol for something he thought was better.
‘This is a guy who makes such a big deal about his character. He has no character. He is a fake. If there was any character in that first marriage, it all belonged to Carol.’

One old friend of the McCains said: ‘Carol always insists she is not bitter, but I think that’s a defence mechanism. She also feels deeply in his debt because in return for her agreement to a divorce, he promised to pay for her medical care for the rest of her life.’

Carol remained resolutely loyal as McCain’s political star rose. She says she agreed to talk to The Mail on Sunday only because she wanted to publicise her support for the man who abandoned her.

Indeed, the old Mercedes that she uses to run errands displays both a disabled badge and a sticker encouraging people to vote for her ex-husband. ‘He’s a good guy,’ she assured us. ‘We are still good friends. He is the best man for president.’

But Ross Perot, who paid her medical bills all those years ago, now believes that both Carol McCain and the American people have been taken in by a man who is unusually slick and cruel – even by the standards of modern politics.

‘McCain is the classic opportunist. He’s always reaching for attention and glory,’ he said.