Imagine a boy running, picking up speed as he nears an open gate and leafy avenue beyond. Freedom. A man is running behind him, trying to catch up; a teacher calling for him to stop. He too gathers speed until he falls. The boy glances behind and sees his teacher spreadeagled. He stops and walks back. “You all right, Sir?” he mumbles. Once assured that the man is unhurt, he turns on his heels and continues his flight from school. The incident has an audience: a group of headship candidates on a tour of the school. For most of them it’s the icing on an inedible cake. No way.

Wouldn’t come here, not for all the tea in China. For Steve Morrison, however, the boy’s concern for the prone teacher is a sign of hope. A child he can do business with. A small hook, but one among many with which he can winch the school out of special measures.

Seven years on, Mr Morrison, headteacher of Kingsdale school in Dulwich, south London, can look back on that defining moment and know that he was right. He is doing business with children at Kingsdale - every one of them, according to the last Ofsted report in 2002, which cleared the school of serious weaknesses. The school, said inspectors, does not give up on any child even though it has some of the most challenging children in London.

In 1998, when Mr Morrison took over, Kingsdale had been in special measures for two years. The percentage of children achieving five good GCSEs was down to 15 per cent, there were more than 280 exclusions a year, including 34 permanent exclusions, and attendance was a shaky 82 per cent. The school buildings, though raised in the 1960s by the London County Council in a spirit of optimism for the future of comprehensive education, had become a liability: dingy, dilapidated, with long corridors that were a breeding ground for bullying and truancy. A former member of the Southwark behaviour team in the early 1990s remembers those corridors as places “where you would think twice about challenging children”, and the dining hall as a place teachers would look into from the outside, but rarely venture. She also remembers some of the most inspirational teaching she has seen anywhere. Some of those teachers are still there, buoyed by Steve Morrison’s leadership.

This year the GCSE pass rate will touch 60 per cent; attendance has been hauled up to 92 per cent; exclusions are down to 20 fixed- term and one permanent, and Kingsdale has set a record as Southwark’s highest performing community school for the past three years. The roll has risen from 900 to 1,225 and it is in the middle of a pound;28 million redevelopment, with pound;12 million already spent. The initial pound;12 million, raised with the support of School Works and The Architecture Foundation, came mainly from the DfES but also Southwark Council and Kingsdale itself. The second tranche, a further pound;16 million, has come from the DfES Building Schools for the Future programme. The corridors that ranged riotously around a scruffy quadrangle have been knocked out to make way for a stunning atrium with a soaring membrane roof, which rivals the Great Court at the British Museum, and at the heart of which is a pod-like, double-skinned geodesic auditorium. This architectural makeover has been feted by the design media as “the most important school building completed in Britain in a very long time”.

Kingsdale becomes a performing arts specialist college in September, so the second tranche of pound;16 million is now being spent on a new music and performing arts suite, on-site sports facilities, hospitality, catering and business studies suites, and an internet cafe. Pupils are on a high. Devika Parti, 14 and in Year 9, is part of an accelerated learning group and has already taken some GCSEs. She says: “Every day you are willing to come to school because it is so bright and beautiful, but also because we are always learning something new. Our teachers are always encouraging us. All of us.”

It’s the kind of happy-ever-after ending we like in education. But the real narrative lies in how such improvement is sustained. The challenges faced by Steve Morrison have not gone away. Indeed they are multiplying. Not only is Kingsdale, which draws in some of London’s most deprived children, surrounded by some of the capital’s most desirable streets and possibly the highest concentration of independent schools in the country, but now it is being squeezed by a pincer movement of academies: seven are planned for Southwark.

Every secondary school in the borough, apart from Kingsdale and the nearby Charter (a new-build school that opened inSeptember 2000), is being turned into an academy, which may squeeze the Kingsdale intake further as parents head for the new. Mr Morrison is rolling up his sleeves further. He challenges any academy sponsor, he says, to do a better job than he is doing. There’s no magic fix to school improvement. Turning a school around takes time, dedication, humour, clear-sighted intelligence and, above all, a liking for children.

Steve Morrison arrived as head with his eyes wide open. He’d been a senior teacher and head of maths in the school in the 1980s so he knew what he was letting himself in for. Kingsdale draws children from across south London - Bermondsey, Peckham, Streatham, Brixton - many of them because they can’t get in anywhere else. Up to 80 per cent are from ethnic minorities, with a high proportion of refugees and asylum seekers, and with the highest number of Afro-Caribbean boys of any London secondary. As there are 13 girls’

schools within a three-mile radius, a gender imbalance is inevitable: three boys to every girl. More than 50 per cent are on the special needs register, and two-thirds are eligible for free school meals. Pupils trail up from Gipsy Hill, where they get off buses and trains, along Alleyn Park, one of the most affluent streets in London where grand Victorian semis and 1930s villas carry pound;2 million price tags. Children from these streets are heading for Eton and Winchester.

Kingsdale’s immediate neighbour is Dulwich College prep school, where 4x4s queue to disgorge manicured sons, cricket bats in hand. Walk down the road and turn the corner and you step into the neo-gothic grandiosity of Dulwich College itself. Kingsdale has long been viewed as an inner-city blot on this idyllic landscape by Dulwich “villagers”. It’s not every head who, when one of his pupils mindlessly trails her hand along a wall, knocking blossom from the much-loved shrub of a neighbouring resident, will receive phone calls of complaint from an MP and several councillors.

Kingsdale’s population remains turbulent, but these days if you stand and watch pupils arriving and leaving at the beginning and end of each day, you will find a peaceable, well turned out, good-natured crowd, with hardly a hood in sight (they’ve been banned, a subject of lively debate in the school council). When things do kick off, PC Ian Templeton, Kingsdale’s full-time community policeman, is swift to respond, but he is just as likely to be found reading with the hardest nuts in their homes, as meting out justice.

In the early days of Steve Morrison’s headship, staff spent long hours in minibuses hoovering up roving pupils. The head himself travelled with them on trains at the beginning and end of the day. He hired two full-time attendance workers and introduced electronic registration - now commonplace, then groundbreaking - which is taken at optimum times of the day to reduce truancy. Breaks were abolished and concentrated into a single one-hour lunch break, and lessons lengthened to maximise staff supervision efficiency.

The issue of race is never far away. Steve Morrison shed half his staff when he arrived; some, he says, were not prepared to work with a black head. He is impatient with parents, white and black, who are reluctant to send their children to a school with so many black children in it. The black Africans in his school are high achievers, 70 per cent of them attaining five GCSE passes, many of them accelerated learners. It is common for Kingsdale children to take GCSEs early, as early as Year 7, particularly in maths and languages. Many children attend its Saturday school.

Alongside the bespoke academic provision runs a whole suite of vocational options. And they make a lot of music. The West End is peppered with ex-Kingsdale musicians; the school’s Brazilian drummers have performed at the Royal Albert and Queen Elizabeth halls, a high percentage of children take music GCSE and nearly all pass, at least one-fifth achieving A*. The school offers 15 music scholarships - intensive one-to-one tuition in singing or an instrument - and this is expected to double next year with specialist status; children who have come in at 11 with no formal music experience usually have reached grade 8 and beyond by the time they leave at 16. Mary Graham, an assistant head, head of performing arts and a passionate musician, has been at Kingsdale for 33 years. As a young Cypriot, who came with her family to London aged 14 with no English, music was her route to success. She wants it to be the same for the many children at Kingsdale in similar circumstances.

Steve Morrison is impatient of journalists who, he thinks, come with negative preconceptions, and is the master of short shrift. Kingsdale has suffered appalling press coverage in the past and though it has enjoyed critical acclaim for its architectural rebirth, the school remains vulnerable and Morrison remains vigilant.

But he does not underestimate the job in hand. A redesign does not make a school: success, he says, involves a long haul in which a clear vision is backed by sweated attention to detail. He came with a “huge reputation” as a maths teacher having turned the maths department at Geoffrey Chaucer, where he was also deputy head, from the bottom to the top performing maths department in Southwark within 18 months. He made it clear that he wanted to oversee a similar transformation at Kingsdale - in every department.

Seven years on, he says he is only halfway there. Staff turnover has greatly reduced, but when prospective teachers come for interview he warns them that the job is not easy. “When I first came I used to tell people who came for jobs that it’s not as tough as it looks. Now people say I am talking down our success, but the job is not yet done.”