Heather Mills: All her troubles seem so far away

What is it about Paul McCartney's new fiancée that people find unsettling?

What is it about Heather Mills? She should, by rights, occupy the same place in the nation's affection as she does in the heart of Sir Paul McCartney, the ex-Beatle she is soon to marry.

At 33, she is beautiful and brave, a former model who lost a leg in a road accident and has campaigned vigorously for disability rights and for the banning of landmines. She is intelligent, vivacious, an adornment to any magazine spread or television chat show. She's almost a Princess Diana Mark II, a good causes activist who is to marry one of the richest and most eligible men in the country.

And yet, there is something that stops us from emulating McCartney and reciting poems and singing songs in her honour. It used to be said that Linda McCartney was the most hated woman in Britain, if not the world. For a generation of women, Linda was the witch who stole their idol's heart – someone who, despite Paul's unrelenting devotion to her and his obvious marital bliss, could do no right. Excellent mother, home-builder, decent photographer, right-on vegetarian, animal rightist? Forget it, Linda was always the woman who denied them Macca.

Time has moved on and McCartney does not occupy the position he once did, so it can't be that. Not even the most die-hard Beatles fan would surely be sticking pins in Mills's image for marrying Paul. Is it because in this country we are embarrassed by open displays of strong emotion, that when McCartney talks repeatedly of his love for her, we reach for the off switch, that his poems and songs dedicated to her cause us to cringe? Up to a point: if McCartney were American, his fellow countrymen would have lapped up every tiny detail of how they met, fell in love and are to wed.

Or is that we are suspicious of do-gooders, wondering in our darkest moments whether theirs is a crusade of self-promotion as much as one of helping others? Slightly. We became cynical at endless pictures of Princess Diana in minefields when her marriage was on the rocks or her midnight visits to hospitals with the press in attendance. The Queen of Hearts tag, which could now be claimed by Mills, is as much an object of derision as admiration.

Or, perhaps we're just resentful of success. Here is a young beauty about to marry someone worth an estimated £700m. Hmmm. McCartney may be loaded, but he is not extravagant. He is not an Elton John, given to flash parties and baroque wardrobes. He is a semi-recluse, an idol who goes to great lengths to guard his privacy, someone who has lived for the past 30 years in rural isolation, bringing up his kids with Linda.

He is also moody and introspective. His children were devoted to their mother. They are successful and speak their minds – making Mills's entry into the family especially difficult. And, he makes no bones about it, he still adores Linda, seeing her in squirrels in the trees, talking to her every day, seeking her approval for marrying Heather. So life with McCartney will not always be easy.

What is it then, that causes us to hang back, to pause a little? The answer is Mills herself. There is something about her that is almost frightening. She seems too perfect, her story too colourful, too dramatic. Few people, say her critics, are as driven, as single-minded, as strong-willed as she. And we find that unsettling, hard to cope with. When her father comes out to say his daughter is not a gold-digger who hunts down rich men, there are some who wonder if he protests too much.

For one so young (she is 33), her odyssey seems truly extraordinary. She was abused as a child, ran away from home at 13, joined a funfair, slept rough in London and, at 14, was woken one night by a tramp urinating on her hair. Blessed with a striking figure and fierce ambition, but lacking any formal qualifications, at 16 she became a model, posing, sometimes topless, for swimwear and lingerie shoots.

By an amazing coincidence, her mother also lost a leg in a road accident, and later died from her injuries. Despite her looks, Mills realised she was not perfect enough to make her fortune from modelling. At 18 she was running her own model agency. A year later, she was moving among London's cosmopolitan party set, associating with the likes of Adnan Khashoggi, the Middle East arms fixer.

She married Alfie Karmal, a computer sales director, an older man with children from a previous marriage. After two years and two ectopic pregnancies, their relationship was over. She became a volunteer aid worker, delivering supplies to refugees in war-torn Croatia.

Then, in a cruel twist of fate, considering she had spent much of her time travelling across Balkan minefields without a scratch, Mills came back to London in 1993 and was hit by a police motorbike, sustaining head and chest injuries, as well as losing a leg.

If all this is not breathless enough, Mills herself is happy to spice up the story, telling how she lost her virginity at 16: "Lovemaking was incredible, sex was everything I'd ever dreamed of." Her breasts were too big, so she had an operation to take them down from 32E to 32C. Her memory of the accident, she says matter-of-factly, was of seeing her leg in the middle of the road. And she was self-possessed enough to sell her story, regaling the world with how she and her boyfriend made love in her hospital bed.

"By the time he left, he looked in need of crutches himself," she said. If anything characterises her story, apart from being incident-packed, it is her intimidating self-discipline. "I have always wanted to be in control," she once said. "I didn't drink for years. Even now I can't handle anyone having a joint." Even when sleeping rough she was not depressed, because "I always knew I was going to go somewhere".

A lesser person might have crumpled after her accident, but that singlemindedness saw her emerge even stronger: "What is the point of sitting around feeling sorry for yourself? Even if you are a mother or disabled, there is always work you could do to help the community."

She resumed her modelling career with limited results, and became a public speaker with far more success ("I am the No 1 woman speaker in Britain, No 3 in Europe and No 7 in the world," she boasted) and argued passionately for the disabled and against landmines. She swam, danced, played tennis, rollerbladed and fell in love, again and again.

She called one wedding off in 1995 and another, to Chris Terrill, a TV documentary-maker, in August 1999. According to his friends, Mills scrapped the private register-office wedding because she said it was not romantic enough. She did, though, want to go through with a humanist ceremony and celebration, the rights to which had been bought by Hello! magazine. Terrill said that would mislead people and cancelled the whole thing.

By then, and it is difficult to imagine this did not influence her thinking with regard to Terrill, she had met Paul McCartney. They had become firm friends after meeting at an awards ceremony and the ex-Beatle was due to be a guest at the wedding. Soon after its cancellation, Mills and McCartney embarked on their affair.

McCartney at that stage was at a low ebb. Linda, his companion for 30 years, was dead, his children had grown up and were leading their own lives. Stuck in the cocoon that surrounds any major celebrity at the best of times, he was, say friends, very lonely. Suddenly he was head over heels with Mills, a vibrant, passionate personality.

Mills moved to be near him and altered her ways, no longer eating the occasional piece of meat but joining him as a total vegetarian. They make a good pair. They both like tugging at consciences and have little difficulty in talking about things that many people prefer to keep hidden. "People either feel threatened by me or they admire me," said Mills. "Those who criticise tend to be those who do the least for others."