Mark Johnson was eight years old when he started to see a psychiatrist about his violent tendencies. That was the same year he first got drunk. Three years on he took heroin in a squat.
His descent into a world of drug-fuelled crime, addiction and homelessness is powerfully recounted in his memoir, Wasted. Even Mr Johnson himself is not sure how he survived the onslaught of crack, heroin and alcohol for so many years. Some higher power must have been at work, he muses.
Now 38 and clean for the past nine years, Mr Johnson is not about to flout his good fortune. Instead, he is on a path to prevent other marginalised teenagers from following in his footsteps. This year he set up a new national charity called User Voice, which aims to ensure disadvantaged young people are properly supported and heard at the highest level.
"The policymakers don't know the nature of the problem out there," he says. "And the people who do know aren't engaged in any meaningful dialogue. The further down the ladder of deprivation and poverty you go, the less articulate people become. The only way they can express themselves is through antisocial behaviour."
Mr Johnson speaks from personal experience. Born to a violent father and mentally unstable mother in the West Midlands, his home life was volatile. He preferred to take his chances out on the streets with his mates.
"We'd get drunk and go out spitting, swearing, smoking and hitting any little kids that got in our way," he says. "The group accepted me, even if they did have a negative effect. I could not talk about my feelings so I used chemicals to forget and change how I felt."
The turning point came when the crack and the heroin stopped working. "I sat in a doorway on Oxford Street (London) and just wailed." He then enrolled in intensive year-long rehabilitation therapy.
"I'd robbed, stolen, lied and cheated to everyone who'd ever come near me. I had to unpick all my deluded thoughts and actions. They were all I'd ever known."
But Mr Johnson fought back. He won a Pride of Britain Award in 2005 for his tree surgery business, which specialised in employing people like himself, and became a special adviser to Prince Charles. He still travels around the UK and the world, exposing the shortcomings of the criminal justice system.
His story has hit a raw nerve with excluded pupils from his old school, King Charles I in Kidderminster. Once he'd given a presentation at the school, a group of youngsters hung back afterwards to chat with him.
"A few of us were looking at each other during the talk," says Nick*, a 16-year-old pupil. "There were too many similarities between Mark's life and ours. It was uncomfortable. I listened to him and thought, `is this where I'm heading?'"
Nick can relate to Mr Johnson - his father is a violent alcoholic as well. So is Nina's, although her dad hasn't been around for a long time. Instead, her mother's boyfriend beats her up. Paul's dad is a cocaine addict and dealer with a terrifying temper.
Kerry, 15, has given up on her dad, who drinks and smokes cannabis most of the day. Unsurprisingly, she is not "emotionally available to learn," Mr Johnson says. She's been excluded from nearly all of her eight different schools and has been suspended about 20 times. She loves a good fight, loves the buzz of it. No one has sat down and asked her why.
"When I smashed this girl's face, I felt brilliant. It was like a drug," she says. "I could channel all my anger. The girl went to my mum and complained and all my mum said was, `Fair play. You fucking deserved it'."
It mirrors an experience Mr Johnson had as a 10-year-old boy, when he beat up an older kid, breaking his screw-in teeth in the process. Mark's dad was impressed by his son's fighting prowess. "It's one of those rare moments I felt real love for my dad," he says. "I learnt a lot from him."
The group has been working together for the past 18 months - ever since Mr Johnson met them at school. They understand each other implicitly. Experiences are met with knowing nods from the others, who share similar horror stories from their short lives. It's the first time they have confided in an adult, and they say it is a relief to get it off their chest.
"People who haven't been through it can't understand," says Kerry. "They say, `I know how you feel', but they don't, they can't begin to imagine."
Mr Johnson agrees. He talks of "normal people" with loving, caring families and opportunities and "us", the outcasts of society who have to work doubly hard to achieve. But he is living proof they can get there.
"Teachers and social services can be sympathetic and lend an ear, but it's more important to be empathetic," says Steve Fatuga, head of programmes at User Voice. "If you can't help that young person, bring in someone who can."
Mr Johnson believes the warning signs will already be there in primary school. Childhood poverty, deprivation, neglect, abuse or substance misuse are all warning signs that adult crime beckons.
One 10-year-old racked up 30 convictions over a single year when he was taken into care. Now 17, he asks the group: "Was I a one-child crime wave or was I suffering?" Society certainly blamed and labelled the boy for his actions, although Mr Johnson believes he had already been failed through lack of intervention.
But each person must take responsibility for their own actions, Mr Johnson tells the group. No one else will. Unless their behaviour changes, their lives could mimic his. "Statistically, you will end up in prison, you will become an underage parent, you will be dead by 20, you will be a drug addict," he warns them. It's not scaremongering, Mr Johnson insists. These are the facts; without them, they'll struggle to change the direction of their lives.
"I don't say, `you can't do drugs' because most of these young people already enjoy taking drugs, but I do ask them to consider the consequences. Drugs narrow your world experience until you can't see any other way or any opportunities," he says.
User Voice aims to give excluded pupils a new set of skills to help them deal with their problems. With such violent or inadequate role models, they may have no prior reference point to learn from, Mr Johnson says.
Kerry's father - who hits her and then implores her to tell him what a good dad he is - is sending confusing, conflicting messages. Without the emotional tools to handle it, she could become one of Mr Johnson's statistics.
Shallow consultations will not work, he warns. Kerry needs genuine love and support from someone who truly cares and understands and who can give her the skills that will make her employable.
The other crucial thing she will need is a sense of belonging. Friendship, attachment and love are basic human requirements, Mr Johnson says, even if it means creating a mock family unit. "Whatever I have achieved, I have never done it on my own," he reveals to the young people. "There's so much more power in unified groups than individuals."
It may sound like social engineering, concedes Mr Johnson, but what else is there for them? There is a fierce sense of loyalty among this small group of Kidderminster teenagers. They hang on every word he says and describe him as a friend who has done more for them in 18 months than anyone else in their whole lives. It is the closest most will get to a "real" family.
With help from User Voice, they are growing in confidence. Kerry looks at Mr Johnson and sees that he no longer answers disagreements with his fists. She is starting to learn another way. The group has given Nick a new lease of life. "It's the best thing that's ever happened to me," he says. "I don't know where I'd be right now if it wasn't for User Voice, but it would not be anywhere good."
Nick and the rest of the group have now visited No.10, where they met and talked with MPs and civil servants. He is about to start work experience with Saatchi amp; Saatchi, the London advertising agency.
"Without this, I'd still be in Kiddy on the estate," he imagines. "I'd grow up, have a couple of kids and probably be a wanker to them. I'd be unemployed and get smashed. This has made the world so much bigger."
Nick, like Mr Johnson, is breaking the cycle of deprivation and rejection. Mr Johnson is determined that his two sons will receive a better childhood, and his future looks brighter still. A new book about youth crime is due at the end of the year and the film options for Wasted have been sold.
"I reached a point where there were two options for me," Mr Johnson writes in his book. "To accept help and listen to others who had gone through it before me. Or to die."
User Voice is Mr Johnson's way of extending a similar lifeline to today's marginalised young people. They too can learn from one who has been there, done that and just about survived to tell the tale.
"No drink or drugs ever made me feel so good," he says.
* All pupils' names have been changed.