Waris Dirie was circumcised at five, escaped an arranged marriage at 13 and was 'discovered' as a model in London. Her campaign against female circumcision has made her enemies at home in Somalia, so her return there to find her family was fraught with danger, writes Louise East

After four attempts and several days of travelling since leaving New York, Waris Dirie finally stepped out of a plane and on to Somali soil. Carried on the hot desert breeze was the smell of angella, the sour breakfast pancakes eaten every day in Somalia; a routine smell, something you wouldn't even notice. But, for Dirie, it was momentous because it meant she was finally home after 20 years.

"A voice inside told me it was time to go home. I had tried so many times, but was always stopped for political reasons. But this time, I knew it was right to come back. I felt it in my gut," she says.

When she returned, she did so as a UN ambassador, with a career as an internationally renowned model behind her and an autobiography in the bestseller lists. When she left, as a 13-year-old child, however, it was a different story entirely. Born into a nomadic tribe, she spent her childhood moving about the desert looking for grass for the camels and goats, and daydreaming about her future.

"It was a very happy childhood," she says. "I learned so much from how I was raised as a child, about how to value life, and the power of community."

It all ended on the day her father arrived home with a man, who was the wrong side of 60 and walked with a stick, but who was willing to offer five camels in return for a bride. The 13-year old Dirie ran away from home in the middle of the night.

"If he'd at least been handsome, or had something going for him," she says, her eyebrows shooting high in outrage. "But when I saw him, I knew this was not it. I saw the way women were valued; I knew I wanted more than that."

Not only did running away mean cutting all ties with her family, it meant a journey of several weeks on foot through the desert.

"I was lost, I was frightened, I was worried - but I always knew I'd be all right," she says. "It was pitch dark, and there were sounds in front of me, behind me and above me. But I know this land, and I knew the sound a hyena makes, I knew which roar was a lion, and which a wolf. I even know the sound a snake makes. If you can survive the desert, you can survive anything."

She soon needed those survival skills in a desert of a different kind. After working with her aunt's family in Mogadishu, she was brought to London, to work as a maid. Asked about the move from the red desert of Somalia to 1970s London, Dirie can only mimic her own astonishment, eyes wide, head slowly turning.

"Every single thing was different - the people, the way they walk, the way they talk, the way they dress," she recalls. "I had to learn everything. That's the best survival tactic the desert gives you: listen and learn. I made many mistakes, but it was like when I was learning to crawl, and I touched what I thought was a lizard. It turned out to be a snake. Sure it bit me, but I didn't touch one again."

While working as a cleaner, she landed her first modelling job. It was for a Pirelli calendar and one of her fellow models was a Streatham girl called Naomi Campbell. The photographer in charge was Terence Donovan and, just like that, Waris Dirie fell in with fashion royalty. Magazine covers, a contract as the "face" of Revlon and a 15-year career as a top model followed. But ask Dirie how much time she has for the fashion industry now and her answer is fairly succinct.

"Absolutely none," she says. "I was exotic, I was something they didn't get every day, but still I didn't get a lot of jobs I should have, because I was black. Finally I realised, what the hell am I doing?

"Here I am serving myself up on a platter and I'm doing it out of choice . . . I mean 'supermodel', what is that? What do you do? What do you contribute? I wanted to set an example to women, but I was going about it all the wrong way."

In 1995, Dirie decided to speak out about her appalling experiences as a child, when she had undergone female circumcision or female genital mutilation (FGM). In accordance with local custom, the five-year old Dirie had her clitoris cut out and her vagina sewn up, without anaesthetic. She remained that way, until adulthood. It's a custom that still happens to hundreds of thousands of girls each year, despite the frequent deaths through infection (Dirie's own sister died). But in the years since Dirie started work as a UN special ambassador for women's rights in Africa, she has seen seven or eight countries ban FGM.

"First of all, it was something I wanted to share; it was therapeutic. I risked my life, my dignity, even my sanity, when I talked about it, but I realised that this wasn't something I'd heard about or read about - it had happened to me," she says.

"But it was also bigger than just me, and if anything was to be done, I was going to have to do it . . . Right now, there's a little girl somewhere, the same age as my child, about to undergo what I went through, and God, oh God, get me there before it happens."

HER first book, the international bestseller, Desert Flower, told the story of her journey from camel girl to international campaigner, but in speaking out against FGM, she made many enemies amongst fundamentalist groups. Returning to Somalia was dangerous, and it was hard to know where her nomadic family might be, yet the urge to find her mother, whom she had seen only briefly since she left, and to see her country, was too strong. Finally, in 2000, she and her brother, Mohammed, brought her scattered family together for two weeks, a journey she describes in her new book, Desert Dawn.

"To sit with my head in my mother's lap like I did when I was two, to be able to say 'scratch my head, mama', it gave me a feeling that nothing could go wrong or, at least, that it would all be all right," says Dirie with a smile.

Gifts of toothbrushes caused much amused scorn, as did Dirie's inability to keep the cooking fire going. Her mother had never seen a mirror before, but was violently uninterested in the silver-backed one Dirie had brought as a gift. Despite the joy of seeing her family, witnessing the changes to Somalia wrought by famine and civil war was "heartbreaking. It had changed into the worst thing you could imagine, a place where a child the same age as mine could be desperate and sick and hungry. That was the worst thing. The best thing was the hope that's there, the wisdom and spirit and faith. Somebody would suddenly smile and it would throw you off guard again".

Dirie, who now lives in Wales with her five-year old son, Aleeke, has set up a charity, Desert Dawn, to bring better education, health and opportunities to Somali children.

It's unlikely that Dirie was ever a typical model or an average goatherd, but the role of passionate campaigner seems to suit her. Hers is a huge and righteous anger, itching for every kind of change in her country, from proper hospitals to women's rights.

"Don't get me wrong, there's much I deeply respect about my people," she says. "I still believe there is much about my culture that is good. But if you are allowed to torture yourself or someone else, or if you try and own someone, that I don't like. In Somalia, my family would say to me all the time: 'You can't go out like that, you must cover every inch of you. What if a man sees you?'

"I would think to myself: 'There's another thing that needs to be changed. Oh yeah, I'm gonna have to come back.'"

Desert Dawn is published by Virago, priced £10.99 sterling. Waris Dirie's charity, Desert Dawn, is at www.desertdawn.org