"When a kid gets into trouble, people say: 'He just got in with the wrong crowd.'" But me? I was the wrong crowd!"

So states Jamie Lawrence who, at the age of 23, was released from prison having served a four-year sentence for violent robber. Yet three months later he was starting a career as a top professional footballer in the English Football League.

Prison is often accused of teaching prisoners a great deal: how to deal in drugs, how to burgle a house, how to rob a bank - but it's not often that an ex-convict comes out of jail with a success story like Lawrence. Many can't get a job because of their criminal record and feel they have no choice but to descend back into a life of crime.

Lawrence was that exception. He became a top-level footballer and has now made a mission of being and influence and a mentor on disadvantaged youths who might end up in exactly the same downward spiral of bad behaviour and crime that culminates in a prison sentence, like his own.

Lawrence's family came to Britain from Jamaica in the 1960s. "Then, when I was 16, my mum and step-dad decided they wanted to go back to the sunshine. They wanted me to go with them but I liked my sport, so I decided to stay here and lived with my sister. But life was hard. We had no money and I had no direction."

And, although he played football locally and had trials for professional clubs, none signed him. So, disheartened and purposeless, Lawrence and his friends started getting into trouble: breaking into cars and committing other petty crimes. He was eventually caught in a stolen car and sent to a notorious young offenders' institution at Feltham, near London.

Released from custody, but unable to settle to a regular job and still full of energy and aggression, Lawrence slipped back into crime again, got caught for robbery with violence and ended up in Camp Hill Prison on the Isle of Wight - and it changed his life.

Jamie started to play for the prison football team, which was allowed to play local teams on a regular basis - and he consistently played the starring role. "I owe a big debt of gratitude to Eddie Walder, the principal officer of Physical Education at Camp Hill," says Lawrence. "He said he believed in me - that I could be a professional footballer - and it gave me the incentive to go for it."

Walder, an ex-professional player himself, says: "One Christmas we played in a friendly match against a local side, Cowes Sport. "The manager, Dale Young, is a friend of mine and, when he saw Jamie, he asked if he could play for them. The governor saw the benefits, not just for Jamie but for the rehabilitation of prisoners generally, and he agreed."

"I decided that that point we needed to make Jamie a gym orderly so that he could do normal gym duties but also keep himself fit for football."

Dale Young takes up the story: "Jamie was a different class to the rest of the players although he got on really well with them. They all held down full-time jobs and trained just twice a week but, since Jamie worked in the prison gym, he was incredibly strong and fit and it was impossible to knock him off the ball."

"Yes, I was in the gym all day" laughs Lawrence. "I went into Camp Hill at ten stone [63 kg] and came out three years later, super-fit and 12.5 stone [80 kg] of muscle!"

It was the start of his change of life. Soon scouts from professional clubs heard that there was a rather remarkable player amongst the prison population. Various clubs came to look but eventually it was ex-England player Terry Butcher, then manager of Sunderland, who made the offer of a one-year contract.

"Going north was probably the best thing that could have happened to me" Lawrences concedes. "I was away from my old mates and could start afresh. They played 'Jailhouse Rock' when I came out onto the pitch at Middlesbrough for my debut match, but I thought that was a big laugh. I couldn't believe that I'd been watching Sunderland play Liverpool in the FA Cup on TV six months earlier and here I was rubbing shoulders with the same players."

Lawrence's career as a winger in professional football lasted for ten years during which time he went on to clubs like Leicester City and the Premier League with Bradford City. He also achieved 42 caps for Jamaica. At 37, he is now playing for Harrow Borough in the Isthmian League.

But Harrow is only part of his life. There is another side where he is putting to good use his experience of being both at the bottom and the top of the world.

And so, early in 2007, he started the Jamie Lawrence Football Academy with the aim of training and mentoring young players with talent and also giving young kids an identity through football. "They may not become professional footballers but they can make something good of their lives with what talents they've got. I'm like a father figure to them and they say things to me they wouldn't tell others."

His HQ is at Nightingale School, a South London school where boys are sent who are disruptive or not coping at ordinary schools. Jamie's new business partner Carl Samuels was already working with young people at the school when he heard about Jamie and realised that there was a lot of potential in what he was doing.

"Jamie understands where the kids are mentally," explains Carl. He can build and instant relationship with young people. We want to work with kids who risk of being excluded from school (the equivalent of being expelled on a temporary basis) or at risk of offending. We want to re-engage young people into full-time education and football teaches them the discipline and life skills to do this. Some of our kids come from very disturbed backgrounds are involved in stabbings and robberies, even as young as 11."

Head Teacher, Richard Gadd, expands: "We take boys here with a wide variety of problems ranging from ADHD [Attention Deficit Hyperactivity Disorder] or Tourette's Syndrome to abused or disadvantaged kids in care who have social problems. Often they are loners because of inappropriate behaviour or lack of communication skills. They end up having very brief friendships of a couple of weeks with other children and then they say or do the wrong thing and get ostracised. That's why they often join gangs because odd behaviour is more acceptable in gang culture and they can feel part of a 'family'.

"What Jamie has to offer is that he understands why young people get into gang and drug culture and wants to direct them children away from that and give them something to focus their minds on. Everyone's an individual but not everyone fits school but Jamie engages many kids here who didn't attend classes but now they come so that they can play football. Even former complete non-attendees come in most days. Jamie moulds them into a team and it's a social event."

Every day Jamie is down at Nightingale School working with the boys on football training on a small and sloping pitch area at the back of the school.

The lure of football is strong but it takes a man like Lawrence to understand what the game can give to young men: "Firstly, it teaches them discipline. Lads don't like being told what to do. If they don't like history, or English, or maths and they aren't very good at it, they'll hide their inadequacies by being the class joker; the swagger; the clothes. They get into trouble with the teacher. Then they're excluded from school which sets them back further and into a spiral which can lead to vandalism and crime.

"One of the things I'm trying to teach the kids now is that, when you get a knock-back, your confidence suffers but that's when you dust yourself off and you come back stronger. Keep knocking on the door and one day one will open for you. There are kids out there who can take a lesson from me. This is more rewarding than anything else I've done in my life."