Simply Iman

'It just isn't fair for women,' says Iman, kicking off her high-heeled mules and settling back into a sofa, a vision in dark blue denim. 'It's so tough on us when we get older. Just as soon as we start to become more rounded people, we're too old to do things like have more babies if we want them.'

She sighs, long and heavily, and you sigh along with her at the injustice of it all. She is married to David Bowie, has legs where most people's armpits begin and, at 47, is still staggeringly, awesomely beautiful. Nope, she's right: life just isn't fair for women. The ones, like me, that is, who have to stand next to her.

Iman is in a photographic studio, somewhere in the murky depths of South London, and every so often, men working in and around the building sneak their heads round the door to take a peek, not quite believing their luck. She has the tiniest lines around her eyes and large-ish but not obscene breast implants ('It was one of the most stupid things I've ever done,' she says), but a quick inventory of her body confirms the horrible truth: yes, she really is perfect.

She lives in New York but is in London briefly for a promotion with diamond giant De Beers, with whom she signed a million-dollar contract this summer to be, in her words, 'a style icon' for the company. Already the signing has proved controversial. Last month, Iman was asked to tear up her contract with De Beers amid allegations that the Bushmen of the Kalahari were being forcibly removed from their homeland in order for a new mine to be opened. Survival International, a London-based charity that campaigns for the protection of tribal people, had contacted the model to inform her of the alleged situation.

Iman now says: 'Before I agreed to sign the contract with De Beers, I went to South Africa to meet Nelson Mandela and he gave me his blessing. One of the things De Beers said to me was that there will be a warranty that says it is a conflict-free diamond. But if I find out that the Bushmen are being evicted, then as a private citizen of the world, I am totally against it.'

De Beers naturally denies any role in displacing the Bushmen, but whatever the rights and wrongs of the issue, Iman has vowed to speak to a director of the Botswana Centre for Human Rights to discover the truth.

It is a particularly sensitive issue for Iman as she and her family were forced to flee their native Somalia some 30 years ago after the revolution of 1969 put an end to their freedoms. 'Naturally, it is a big concern for me because of what happened to my family. I still miss my homeland, and if I could do one thing in this world, it would be to settle Somalia's differences. My parents are getting to the age where they want to go home to die and they can't.' She stops, crying suddenly. 'I have been back to Somalia and it was the toughest thing. Going back to visit the house we owned before exile. Going to see my old school and home and finding nothing left. Nothing. That's hard. You know,' she says abruptly, 'you've made me cry. I don't cry often, but I always do when I think of my home.'

The Somalis, says Iman, are a tough people and she is no different - a situation partly driven by circumstance and partly by her inherently steely nature. She was tough enough to earn the money as a model to put her siblings through college, and also hard-nosed enough to carry on working when her eldest daughter Zulekha (by second husband, Spencer Haywood, after a brief first marriage in Kenya as a teenager) was growing up.

Iman now regrets that 'work and career were my priority' and subsequently, the relationship between mother and daughter became difficult at times. 'As a parent, you would never do anything intentionally to hurt your child, but there are things I regret about her upbringing. I felt very guilty that she had to grow up with divorced parents - not guilty that I didn't stay with him, but guilty that my child didn't have stability. It's so important to give children a stable upbringing and I felt bad because I thought I'd messed up her life.

'I had a difficult relationship with my own mother at times - my poor mum, she could never do anything right. I'd always be screaming at her: "I hate you, I hate you!"' Iman guffaws. 'But the minute I had my first child, I understood exactly how my own mum felt and said to her: "Forgive me, Mum, please!"' Zulekha now works for her mother's cosmetics company in New York, 'Although I'm not her boss - oh, that would be too bad! And whatever problems we've had, we get on great now.'

Iman's younger child is Alexandria, or 'Lexie', her two-year-old daughter with David Bowie. The couple had been hoping for a baby since they married in 1992 and after eight years and two failed IVF attempts, it finally happened when Iman was 44. Now, it transpires, the Bowies are trying for another baby. 'We are, yes,' says Iman, 'but to be honest, I don't think I can have another. It took so long to have Lexie I think maybe I should just count my blessings, you know? David is happy whatever happens and he loves being with Lexie. Because we are a bit older, we do think about the future a lot more - will I be around for her when she goes to high school, when she goes on her first date? But what can you do? You can't worry about dying, you just have to get on with living.'

Iman admits she is 'the tough one out of David and me. Alexandria is such a daddy's girl and sits on his lap, reading. He sings her lullabies and swears blind that she is musical. And she has his body too - such a skinny little thing! He's a very hands-on dad - we're both hands-on - but he never changes her diapers because he thinks he'll probably drop her. She's a Leo and so am I, so we're both stubborn and ooh, we're gonna have some fights when she grows up!'

Bowie turned down the opportunity of a world tour this year because he didn't want to leave Lexie. The events of 11 September 2001 caused him to acquire 'a degree of protectiveness that may not have been there in quite such an acute way' previously. The family lives in New York and Iman witnessed the events first-hand - initially hearing the first plane hit the North Tower and watching from her kitchen window as the second plane hit the building. 'It was truly horrifying. And the scariest thing was that it was such a beautiful, clear day. Even now, when I wake up on a beautiful morning I have that feeling of dread, of thinking: "Oh God, what is going to happen today?"'

Did she and Bowie think about moving to London? 'Well, no. New York is our home and we feel comfortable there. When Alexandria was born, we did consider living in London, but decided against it. But we do come to London more often now and, of course, David was born here.'

Look for any chinks in the Iman-Bowie relationship and you'd be hard pushed to find many. Bowie recently claimed that, apart from a few minor arguments in their first year together, he couldn't recall ever rowing with his wife. There is a sense that, although both have had turbulent lives, they have found a kind of peace in each other. 'Everything happens for a reason,' says Iman, 'but sometimes I do wish I had met David sooner. Maybe, though, we met at just the right time. If we'd married in our twenties, we'd probably be divorced by now because we were such different people then.

'I do pinch myself sometimes at how lucky I am to have met him. After ten years of marriage, my heart still skips a beat when he enters the room. Do I still fancy him?' Iman shrieks. 'Of course! He looks so good and cool and he's put on a little bit of weight now because of my cooking! But he's such a gentleman and so old-fashioned, always opening doors for me and standing on the outside of the pavement. He's my soulmate and although I didn't realise it, David said he did instantly. He's changed me, too. I'm now less guarded because of him and I feel safe for the first time. When your family has been in exile from the country it loves, feeling safe is something you never take for granted.'

Iman Abdul Majid was born in 1955 in Mogadishu. She was initially called Zahra but her grandfather changed her name to Iman - a male name, a factor she strongly believes helped shape her temperament. Her parents were unusually progressive and because Somali culture didn't encourage female education, they sent her to boarding school. Iman hated being separated from her family and 'held it against my father for years', despite her insistence that they were nonetheless loving parents.

The family fled to Kenya after the revolution and it was there that the course of Iman's life changed. Peter Beard, the celebrated photographer, spotted her on the streets of Nairobi and asked her to sit for him. Iman agreed, but only for a steep fee which she used to pay her tuition fees as a student of political science at Nairobi University. Beard sent the shots to New York's Wilhelmina modelling agency, which accepted her on the spot. They created a rather romantic but totally fictitious tale about how they discovered Iman as a peasant goatherder who could speak no English. Iman, just 18, came to New York and colluded with the myth, hilariously remaining silent during interviews while questions were addressed to Beard, despite the fact that she could speak five languages.

Iman was an instant success. Eager to become a part of the New York scene, Iman did the whole party circuit, indulging, as she once said, in 'everything, everything - the cigarettes, the champagne and the coke became part of the fashion show'. Her career started to rock, too. Her first job was for American Vogue and she went on to model for all the top designers, including Thierry Mugler, Yves Saint Laurent and John Galliano. Perhaps most famously, she appeared as the dancing girl for Tia Maria and was in such demand that she became the first black model to earn £20,000 a day.

Then in 1990 she retired to try her hand at acting, and although she had bit parts in films such as No Way Out and Out of Africa, her film career didn't take off as she'd hoped. More successful was her foray into business with the launch of her eponymous make-up range, designed specifically for 'women of colour'.

Now, she says, life really couldn't be better - 'Yeah, I'm happy. I'm very, very happy' - although her longing for another child is clearly nestling in the back of her mind. 'Well, God willing, it will happen.' She smiles and gives me a hug before leaving to the sound of jaws clanging to the floor. If anyone can make the impossible happen, Iman is most definitely your girl.