'I'm going to give him the visa. I believe him,' she said finally, 'but if he ever turns out not to be the nice man he appears to be, you will inform us, won't you? We would be very interested to know.'

I found Tsedup sitting on the grass outside.

'We've got it,' I cried, but he was too distraught to care.

In him she had provoked the desired response, but at a cost. 'You come from nothing. Your family have nothing. You're just using this English girl to get to the West,' she'd said to him. She had no idea how he had suffered, missing his family all these years, or the depth of his feeling for his homeland.

He had leapt from his chair and, with both fists on her desk, had shouted in her face, 'How dare you insult my family and my country? I am proud of them and I love my wife.' It was his first encounter with a British authority figure and I was sorry that he had seen the ugly side of my culture so soon.

It was a struggle for a nomad in London, an education for us both, and life had not prepared me for living with the pain of an exile. But I was quick to learn, and so was he. I saw through his eyes. Things that were commonplace became exceptional: an escalator ride; using a knife and fork; sitting on a loo. He was sick in cars, claustrophobic on the tube. He slept a lot: this new land was too alien to face each morning. I had to leave him while I went to work, so it was a lonely time for him. He spent his days in a cloud of nostalgia, preparing Tibetan food, patiently re-creating the smells of his homeland in our small kitchen, with chilli and chives, meat momos.

We lived in my parents' rented flat in North London, on the top floor on a hill bustling with traffic. The house vibrated when the buses passed. My mother would come up from Winchester on Mondays and Tuesdays to do her psychotherapy course. In the evenings Tsedup and I sat in the bedroom quietly, while her clients cried through the wall. 'Don't they have any friends?' he asked. He would sit and look at the Heath from the back window, desperate for a vista: there were no mountains, nothing to look up at. The streets were closed in. Tsedup felt the world hurrying past him; there were more people in this city than in his whole country. He had dreams about flying, and his father hunting on the Heath, and woke in a sweat, afraid that the police would get him.

'You are my family here,' he said. 'You're all I've got.' I loved him enough to want to be everything to him, but I was not. Beyond our existence lay another world and a part of him I had yet to discover. Until I saw him in his homeland I would never truly know and understand him.

He spoke to his parents. It was the first time they had had contact in four years. (No mail had got through between India and Tibet.) Nomads cannot conceive of a life without family, and they had been desperate for news of their son. They rode six miles to the only international telephone in town and waited at a prearranged time for it to ring. The whole family crowded round the receiver. His mother had never used a phone before.

She cried into the mouthpiece, 'When are you coming home?' But they told him not to come back until he had papers: it wasn't safe. They could not visit him in England. They would need Chinese passports for that and the likelihood of acquiring them was almost impossible. We waited for his British passport, and my father wrote to Tsedup's father, reassuring him that we were taking care of his son. He received a reply on fragile paper in the most exquisite hand, a silk prayer scarf enclosed. Tsedup translated:

It is almost inconceivable that two families, so very far away from one another, should be joined, as we have been, in the coming together of Tsedup and Kate.

That was how we felt. I wanted to write to his mother. She was illiterate, but I knew that Tsedup's father would read my letter to her. ‘I miss you and I don't even know you,' I wrote. 'But we are both living under the same moon. When I look up at it I will think of you.' Later she told Tsedup that when he brought me home she would love me as one of her own daughters. She had two; now I had become the third. I had not even met them and yet I was part of them, as Tsedup had become part of us.

In England he watched TV for the first time, and it became a window through which he could look and learn about all sorts of things – 'From the leader of the country to how to make pasta,' he said. He spent hours watching nature programmes, learning about animals he had never known existed and observing the microscopic lives of insects. The images blew him away: he had always been close to nature, but never that close. Soon we were watching him on the screen: he became a model and actor. They booked him as an Eskimo, a Cherokee, a Mongolian warlord, but never a Tibetan – most people didn't know what that was. They liked his look, they said, exotic. So he played along: the cultural chameleon. He had the English friends he'd known in India and soon they became my great friends too. He even made some Tibetan friends, although there were only a few in the UK. Most spoke the Lhasa dialect of the capital, which was different from the eastern region of Amdo, where Tsedup was from. But he was lucky enough to find a couple of Amdo friends and they became his lifeline, sharing his memories. He was always elated after he'd seen them.

I found work as a magazine designer and we became more comfortable. One day I broke it to my parents that we were married. 'We have a son-in-law,' my mother cried. We decided to celebrate with those who had helped us through hard times and had an intimate blessing service in a small Hampshire church. It was a joyful day, but we felt the absence of his family. We showed slides of them through the service, to try to make them a part of it, for Tsedup's sake. He saw a picture of his parents smiling inside the tent as he took his vows. The vicar even allowed our Tibetan friends to read a Buddhist prayer. I had never been so moved.

Gradually he assimilated, but never conformed. That would have meant losing a part of himself. He missed his people and resolved not to live like an Englishman. If there was such a thing as a modern nomad that was what he'd become, he said. He wanted to go home, to live his life between two worlds. Somehow we endured the waiting, the bureaucracy and the indifference. The Home Office would not issue a British passport until he had been in the country four years. We had enormous reserves of hope when the waiting got too much. And we had each other. One day, eating chips in a pub on the Euston Road I handed him the visas. After nine years of waiting he was going home.

Tsedup had crossed the widest cultural gap I could ever have imagined and survived. Now it was my turn: I was leaving a glossy, society magazine to go to the Roof of the World. For six months I would live with his tribe as a nomad bride in the Machu grasslands of Amdo. As far as I knew, I was the first western woman ever to have done it. I was making history. My parents wanted to come with us for the first week, to be with him in case there was a threat to his safety and to be part of the reunion. He telephoned his parents to tell them we were coming. His father had ridden back from a three-day hunting expedition. That was all he had wanted to hear, he said.