Interview: Why did the Home Office decide that this model immigrant should be deported?

As a young boy in Nigeria, Damilola Ajagbonna imagined Englishness as being defined by two attributes: justice and fair play.

"I grew up in a country where bribery was rife and inequality was endemic," he recalls. "I knew that such things did not occur in England. I honestly believed that integrity lay at the heart of the English system." He smiles. "My mother says: 'Just look at you and your love for the English people. Look how they've treated you. Look what they've done for you, your white English friends.'"

We're talking in the pub next door to his old school, Greig City Academy (GCA) in Hornsey. Ajagbonna, 19, left last year. As recently as four years ago, GCA was derided as the worst school in north London; in 2002 an Evening Standard reporter enlisted as a supply teacher and described how she was thrown across a desk by a pupil and threatened with rape. The atmosphere, she alleged, was "like a war zone".

When he arrived in London from Nigeria, aged 11, Ajagbonna came straight to GCA, then known as St David and St Katharine School; it became the UK's first City Academy in 2001. He graduated last summer with 13 GCSEs, excellent A levels and the offer of a place at Fitzwilliam College, Cambridge. Head boy at GCA, he has spent two years serving as an adviser to Unicef, and has been an intern at the political think-tank, Demos. Ajagbonna, a Sunday-school teacher at his local Pentecostal church, was the first pupil in his school's history to accept an offer from Oxbridge. It was an achievement which attracted widespread attention – not least at the Home Office, where his application to Fitzwilliam proved the trigger for their ongoing attempts to have him deported as an undesirable alien. Having had three appeals rejected, Ajagbonna is close to the end of the legal process that will culminate in his being forcibly removed to Lagos.

Ajagbonna is articulate, engaging and has a sense of irony that has been tested to its limit since Whitehall's actions caused him to lose his university place. Before we settled down here, at a table in The Three Compasses, we met in the reception area of GCA, a school which, under the stewardship of head- teacher Paul Sutton, has continued the process of shaking off the appalling reputation cemented by the Evening Standard article. The atmosphere around the school was calm and respectful; as we made the short walk to the pub, "Dami" was warmly greeted by staff and pupils alike.

Sixty per cent of GCA pupils qualify for free school meals, and between them they speak almost 80 languages. Ajagbonna is probably the only one who would describe his predicament as "Sisyphean". "GCA," he says, "will never be Eton. But you can go to Eton and come out with three Fs; you can come here and go on to do a degree." He's carrying a new canvas holdall, containing legal documents and books. "Nice bag," I tell him. "Just because one is about to be unfairly deported," he says, with a mock Wodehousian intonation, "does not mean that one cannot be stylish."

He grew up in Vom, northern Nigeria, where his mother Nwuli, a haematologist who suffers from sickle-cell anaemia, still lives. He came to Hornsey in May 1999 after his father, an entomologist, suffered "a mid-life crisis" and disappeared. Nwuli sent Ajagbonna to be adopted by her sister Ann, an NHS nurse, and her husband Bill, a Tesco manager.

GCA is situated between the affluent areas of Crouch End and Muswell Hill (where Ann and Bill lived when Ajagbonna first came to England). But the school draws most of its intake from Tottenham estates such as Broadwater Farm; when Ajagbonna arrived, in year seven, he was mocked for his accent and his ignorance of urban life; Vom is a village of 500 inhabitants, with intermittent running water and no telephones. As a result of that taunting, he now speaks impeccable Radio 4 English. "I was nine when my father left," he says. "Because I was the youngest – I have two sisters and an older brother – I was very close to my mother. I used to sleep in her bed. When I came here, the shock was such that, in order to stop myself from disintegrating mentally, I totally focused on England, and on my school."

Sutton says that Ajagbonna "was always fascinated by state education. When he arrived, the school was deteriorating at an incredible rate. He was an excellent mentor for younger pupils. He has a strong altruistic streak and he'll talk to younger students in a considerate yet forceful manner. Damilola is a very special person."

Sutton speaks of Ajagbonna less as a beneficiary of GCA's regeneration, more as a vital collaborator in its accomplishment. Even though Ajagbonna has moved to Luton (in his final year at school, he was getting up at ' 4.30am to catch the first of three buses to bring him here), the two still meet regularly, for mutual support. Sutton, 49, who was, coincidentally, born in northern Nigeria, arrived as GCA's head in 2004. In January 2005 he broke his neck playing hooker for a Saracens XV and is now confined to a wheelchair, with minimal movement in his hands. He returned to work in October of the same year.

"He was lifted up in the scrum like a rag doll," Ajagbonna says. "He died twice but they managed to resuscitate him. Then he contracted MRSA, and nearly died again. This is a man who has been to the gates of Hell, looked the Devil in the eye and said: 'Go away. I'm not finished yet.' I believe that is one reason why this school is so vibrantly resurgent. You're constantly asking yourself: with somebody like this at the helm, what's your excuse for not working hard?"

When Ajagbonna arrived at the school, "there were fights every day. The only good thing about that was that, when kids from other schools saw your blazer badge, they would never pick on you – however small you were." In Muswell Hill Library, on a Saturday morning, he helped teach GCA's less academic pupils to read. One of them, he says, has since gone on to university.

Ajagbonna's model career faltered when he filled in the Ucas form to apply for Cambridge. "They asked about my residential status," he says. "Anomalies began to emerge. My auntie was supposed to have sorted out the papers for my adoption, which would have given me a British passport. I'd lived for six years believing that I was under her legal custody. In fact, the Home Office had sent her a form in 2001; she'd put that process in the hands of a family friend, a solicitor who's now in jail for fraud. My adoption was never correctly completed. My aunt feels terrible about this. I only became aware that there was a problem when I was applying for university. When you're 13 you don't question whether your guardian has followed the correct procedure regarding your immigration status."

"So you're still a Nigerian citizen?"

"Yes, although I haven't seen my passport for eight years."

Under a slightly more compassionate regime, none of the problems relating to his adoption would have mattered. "The UK," Ajagbonna explains, "has a seven-year concession policy. This means that, if you have lived here as a child for seven years, you are permitted to remain indefinitely. I entered Britain in May 1999. I turned 18 on 16 March 2006. So I hadn't spent the required seven years in the UK: I fell short by six weeks. We requested that the Secretary of State should apply special dispensation, but the answer was no."

Ajagbonna , who left school in 2006, lost his place at Fitzwilliam after the Home Office announced it had begun the process of attempting to deport him. Eliciting this first, negative response from the Government department, Sutton says, proved more challenging than anybody had imagined.

"John Holt, our head of sixth form, had been phoning the Home Office on practically a daily basis," he adds, "asking them to make a decision, because they were basically fannying about. I wrote to them pointing out that this was an exceptional young man who has made nothing but a positive contribution to our society. That meant nothing to them, it would appear."

Ajagbonna's grades at A level – three Bs, in English, drama and biology – were slightly poorer than Fitzwilliam's offer demanded, but Sutton says that, given Ajagbonna's background, he would normally have expected the university to exercise flexibility, had it not been for the uncertainties relating to his passport. Sheffield University, Ajagbonna's second choice, accepted him on its sociology and political science course, but he was unable to enrol because of his threatened deportation. His plan was, and is, to graduate, complete a PGCE, then return to GCA as a teacher (after he left GCA he worked there for a year as an administrative assistant). Sheffield deferred his place until the current academic year, which began last month.

There followed a gruelling round of hearings before Asylum and Immigration tribunals. (Ajagbonna's legal defence has been funded by his aunt and uncle.) The first, in October 2006, was heard by Judge Malone. A few days after our first conversation, I met the 19-year-old in Luton, at the office of his solicitor, David Adesina, of Nelson Bridge and Co. Adesina, who is also Ajagbonna's church pastor, explained how the appeal had been lodged on multiple grounds, notably the strictness with which the government had applied the seven- year rule. "We argued that the spirit of the seven-year rule was met. The essence of that policy is proof of integration: having lived here for seven years demonstrates that this child has been integrated into British society. Our argument was that seven years minus six weeks does not mean that this person has not integrated acceptably."

Judge Malone's findings, in a highly sympathetic report, included the assertion that he considered Ajagbonna's contribution to society as a whole, and his school in particular, as "remarkable". Malone states that: "He would appear to be multi-talented. It is no mean achievement for him to have obtained an offer of a place at Cambridge. He is clearly an outstanding young man. He would appear to be both keen to learn and to give. I know that he has been eager to perform mentoring services."

Malone allowed Ajagbonna's appeal against deportation, with the proviso that it be approved by the Home Office. "When we saw the findings," Sutton says, "we all thought: 'Hurrah. Somebody, at last, has shown some common sense.'"

Their optimism was premature.

"We wrote to the Home Office six times," says Adesina, "requesting that they communicate their decision in the light of Malone's findings. In July 2007 they replied, stating that we were refused, and had five working days to appeal."

The case was referred to a second Asylum and Immigration tribunal, in August 2007. The judge, Geraint Jones, dismissed the appeal, observing in passing that it made no difference that the appellant was "a jolly good chap".

"And that," I ask Ajagbonna, "was the exact phrase he used?" "Yes. We appealed against that decision, and asked for what is termed leave for reconsideration of the case."

On 23 October this year, a month after his course had begun at Sheffield, Ajagbonna, still in Luton, was informed that his request for reconsideration had been refused. Last week, he lodged his final appeal against the decision. If and when this fails, he will have exhausted every option short of appealing for a judicial review before the law lords; Ajagbonna has no idea how he would fund such an action.

The persistence with which the Home Office has prosecuted this case surprised many observers – not least because Ajagbonna is easily the most distinguished product of a school which has been ridiculed in the conservative press for its "flagship" status in the City Academy scheme supported by both Tony Blair and Gordon Brown. The authorities' unforgiving pursuit of Ajagbonna is in marked contrast to their apparent attitude to the 430,000 more secretive illegal immigrants and failed asylum-seekers who, by the government's own reckoning, were still in the country in 2005.

"Recently," Ajagbonna tells me, "my auntie asked me whether, if I'd known what would happen, I would have come to the UK. I say, with my hand on my heart, that I would not. Not if I knew I was going to lose the dignity I fought so hard to earn. I feel like an animal, caged. Even in poverty I would have a chance to improve myself. And that's what I came here to do: improve myself. I feel totally ground down. I am at the mercy of people I don't even know."

"How has it affected your mental state?"

"I'm depressed. How couldn't I be? How do I define myself now? What am I? I am clearly, in their eyes, not British. I'm not Nigerian; I have lost that contact. I haven't seen my mother since 1999. So who am I? Mr Sutton told me I'm like a water hyacinth, that has no roots at all, but simply floats."

"Except that the water hyacinth is a plague."

"It used to be, but I believe they eventually found a use even for that." His experience has every quality, I suggest, of the kind of nightmarish injustice that might have been scripted by Hitchcock.

"The Home Office didn't have to hunt me down. I went to them. When I learnt there was a problem, I tried to do things correctly. The best analogy I can think of is: you fall asleep, you wake up and you discover you have been robbed. You go to the police and explain what has happened, and they arrest you. I feel as if they have taken my life away from me."

With his final appeal pending, Ajagbonna has lost his chance of attending university for another year. He spends his time at home in Luton, reading, and occasionally comes down to help out at GCA. At one point, while I was writing this article, he called and said he was becoming attracted to the idea of setting himself on fire outside Westminster. "You sound as if you think I'm joking," he said. "Well, I'm not."

His friends, both in Bedfordshire and Hornsey, continue to support him in a case which, viewed in the broader context of natural justice, appears to be one of the most absurd wastes of public money since the Lady Chatterley's Lover obscenity trial. They, like the demoralised young student, remain astonished that his predicament could have arisen in the first place, let alone continue for so long. Their anger at a bureaucratic process that has paralysed a young life is coloured by a deepening sense of gloom and bewilderment. His academic past is receding to the point that he speaks of it almost as another life. His future, which once seemed so promising, is now impossible to predict. And when it comes to the present, the only certainty about Damilola Ajagbonna's situation, to borrow a phrase that has become all too familiar from news reports concerning other young victims of circumstance, is that he found himself in "the wrong place at the wrong time": Britain, 2007.