[McCain] was shot down over Hanoi in October 1967 on his 23rd mission over North Vietnam and was badly beaten by an angry mob when he was pulled, half-drowned from a lake.

Over the next five-and-a-half years in the notorious Hoa Loa Prison he was regularly tortured and mistreated.

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.

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.’

‘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.

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.

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.

‘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.’