It looked like a typical five-a-side tournament, with three pitches set up on the school's sloping grass, a barbecue and drinks stall, portable loudspeakers pumping out music and teams warming up and joking around in the sunshine. But next to the table with the trophies was a desk covered with a series of neatly laid-out advice sheets: Metropolitan Police factfiles on drugs, theft, assault, graffiti and weapons.

Six miles north, the family and friends of David Idowu marched on Downing Street in an anti-knife protest. Nearly three weeks ago the 14-year-old became the nineteenth teenager to be murdered in London this year.

As the games kicked off, Jamie Lawrence discussed his vision: salvation through sport for inner-city children stuck on a conveyor belt dragging them along a familiar production line; trouble at home, problems at school, exclusion, alienation, poverty, crime and punishment. Lawrence wants to help to end the occurrence of tragedies such as the death of Idowu and the smaller sadnesses that go unreported and unnoticed - the young lives without hope or happiness, the potential that will never be realised.

Lawrence's faith in the power of football to leaven entrenched social problems may sound idealistic. However, the 38-year-old former Leicester City and Bradford City defender and midfield player is anything but naive. “My mum and dad looked after me properly, it wasn't a broken home, but they went back to Jamaica when I was 17,” he said. “I was left in the big wide world on my own and finally ended up in prison. I started robbing and all sorts, got arrested, got three years for robberies, assault and theft. I did one year out of that, got out again and reoffended after three months.

“I was earning £50 a week as a mechanic. I was getting paid on a Friday and the money would finish on a Friday, and what do you do after that?”

In fact, there was one other thing he could do. The boy from Battersea in South London could play football. He was spotted playing for his prison team on the Isle of Wight and after his release made his way up the pyramid until he was an established top-flight and Jamaica player known for his colourful hairstyles.

Last year he formed the Jamie Lawrence Football Academy, based at the Nightingale School in Tooting, South London. Its 40 pupils are boys aged 11 to 16 with behavioural, emotional and social difficulties who have been excluded from mainstream schooling. Students play football for at least two hours a day, attend workshops on topics such as drug awareness, anger management and personal development and are offered mentoring. Lawrence hopes to develop a network of academies across England.

“This is my way of getting their attention - I can share my life story with them and try and teach them the right way to live,” he said. “Hopefully they can learn from what I've been through. If I was just coming in as a professional footballer, they wouldn't look at me with respect. But because I've been there, in prison, come out and done well, they respect me.”

Using football, the children improve their teamwork and discipline - swearing is punished by press-ups. Carl Samuels, the academy director, believes that violent crime among youths is on the increase. “There's not one answer, it's a whole spectrum of things,” he said. “Absent fathers, economics, racism, lack of education. Society's giving our young people options we wouldn't like them to take. Students here have carried weapons, some are probably still engaged in gang activity, some have turned the corner. Whatever they're doing outside, on our time we can make sure they're behaving respectfully. Students who haven't been to school in three months come here regularly.”

One 16-year-old at Tuesday's tournament for the academy's pupils is a repeat offender who has just started living alone. Samuels is helping him to learn to look after himself, from teaching him how to cook to developing the maturity to not stay up all night with his friends and spend the next day in bed. Another, excluded from school for unruly behaviour, nourishes dreams of becoming a professional footballer.

Of course, few, if any, will be lucky enough to follow Lawrence's post-prison path. But if his scheme can direct them away from the road that leads towards disconnection, rage, violence and grief, that is success enough.

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