There are chunks of William Bell's young life that he can't recall, but the day he will never forget is when his parents threw him out of the family home.

"To be rejected by my own flesh and blood and chucked out onto the streets of London was totally devastating," says William, 21. "My mother dumped my bags on the pavement and said I was no longer welcome. I felt unwanted and useless, as if I had lost everything, but also incredibly angry at what I believed was my parents' hysterical over-reaction. I remember thinking my parents were naïve and quite insane in their insistence that I was a drug addict when all I was smoking was cannabis, as opposed to injecting heroin."

If these sentiments sound familiar, it's because they uncannily echo the words used last week by 20-year-old Jake Myerson to describe his mother, Julie Myerson, 48, the Booker-nominated author whose new novel The Lost Child is due out next week. Angry and distressed at his mother's decision to go public on how they'd disowned him because of his use of skunk, a potent form of cannabis, Jake launched a scathing attack on his mother, calling her "insane" and "naïve" for being "unable to tell the difference between smoking a spliff and being a drug addict".

The story of William is almost a carbon copy of Jake's. Not only do they both come from well-heeled, south London families, but their mothers - both writers in their late forties - have supported each other through their respective ordeals. Both boys were sent packing about two years ago after their habits threatened to damage their younger siblings and destroy the family, and both have had to endure their mothers going public and choosing to write about it.

But whereas Jake remains resolute that cannabis is his friend, William now takes a different view.

"Tough love worked for me," William says. "I had become a hobo who stole from my friends and family and couldn't concentrate for more than five minutes or hold down a job. Now I rent a flat in Balham for £660 a month, I work as a barman in a pub, and I've not touched drugs for nine months.

"A few months ago, I made contact with my parents for the first time. At first my mother was tentative and suspicious because there have been so many false starts. But we got together for my 21st birthday and my father's 50th, and since then I've slowly been accepted back. If I'd never been kicked out, I'd still be using skunk, living like a hermit in my upstairs bedroom, doing f***-all, and making my family's lives a total misery.

"Don't get me wrong, I hated my parents for what they did. Absolutely reviled them. And I have to admit, I feel great sympathy for what Jake Myerson is going through- the loneliness, the depression, the angry incomprehension at being abandoned by the very people who love you. He's been labelled a drug addict and he can't see why.

"But the truth is somebody has to break the cycle. And once my parents washed their hands of me, I was forced to start taking responsibility for myself. It was the hardest thing I've ever done. Hopefully Jake can make that leap, too. Because in the end you realise your parents have thrown you out not because they hate you, but because it's your last chance to find a road back to yourself."

Debra Bell, William's mother, says she is "quietly delighted" with her son's return to the family and that, in time, she is hopeful that tough love will work for Jake Myerson, too.

Debra recalls how Julie contacted her in early 2007 after she had published the story of William's descent into addiction on the web and set up the website Talking About Cannabis as an aid to other parents.

"The similarities between what Julie and I were going through was just extraordinary: we both saw ourselves as dedicated, loving parents with bright sons we adored but whom we'd lost to cannabis. They had become strangers before our very eyes, but we felt so alone in what we were going through, and also terribly ashamed. This sort of thing is not supposed to happen in middle-class families. We began to meet up at each other's houses to share our fears and draw strength from each other."

Indeed, when I interviewed Debra for this newspaper last April, she stoically told me: "I have to accept that what I've done may not work, that William may never find his way home again."

She and her husband, Guy, a barrister, had reached this point of resignation after trying everything, she said, including spending £6,000 on rehab for William at The Priory, and three failed attempts to entice him back into full-time education after he'd dropped out of A-levels (they spent £60,000 on his private education at Dulwich College). But she came to believe that it was only when William took responsibility for himself that his life would begin to shift.

"I know that it's been a nightmare for Julie but I firmly believe she made the right decision both in terms of the tough love and in writing about it," says Debra.

Interestingly, William thinks so, too. "One of the triggers for me changing was a double-page article that I read about myself in the Evening Standard last April, six months after I'd left home. There was a picture of me as a child and when I read it, I was shocked as to how much I resembled the classic psychotic cannabis-addicted stereotype, the sort of person I believed I would never become. I was angry to see my life paraded in the media like that, but it was a wake-up call.

"Initially when I was thrown out, I had about £1,000 that my grandmother had given me and the first thing I did was to buy some skunk. I was sleeping in the Clarendon Hotel in Blackheath, paying £60 a night while I hunted for a flat, but after a week I had to move out because I'd spent all my money on cannabis. After that, I slept on friend's sofas, but I couldn't stay long because I stole from people.

As an addict smoking six joints a day, you live life only for the present. It's all about the next high. Once I got arrested for shoplifting in Harvey Nicks. I took a tracksuit and made a run for it, but I got caught and the police only let me off with a warning because it was my first time."

Deciding to give up weed was a long, painful process that required a complete revolution in how he thought about the world, he says.

"You have to understand that for six years, I had vociferously defended the cannabis culture. It was like I went to war for it. To admit that everything I believed in and stood for was a lie took incredible strength.

"As a 14-year-old, I was told that cannabis was a Class-C drug and that you couldn't get addicted. There was a group of us at Dulwich College who would get together and score skunk at weekends. Initially the effects were subtle and temporary. I was a mad-keen sportsman and I continued playing first-team football, but I started to lose motivation for my studies, and after completing my GCSEs, I just stopped going altogether.

"I look back and see my life as a blur, but that I was like a whirlwind ripping through my family, stealing money and jewellery from my parents and my brothers and being totally selfish."

Physically, he was a mess, too: pale and listless with dark rings under his eyes, his hair was greasy, his teeth filthy, and his clothes reeked of dope. "I knew that it was making me paranoid and physically ill, but until my parents threw me out, I always had them to blame."

Last spring, he says, he began to clean up. "It helped that I'd got a job in a pub and that I had less time on my hands, but at first I took it day by day. I never said, 'this is my last spliff'. I started to physically feel better. I would no longer wake up with my eyes burning, I got my sense of smell back, and I felt more energetic than I had in years."

A few months later, he tentatively got back in touch with his parents. "I wanted to be sure that I could sustain my new lifestyle by the time they saw me. I had apologised so many times that words meant nothing to them and I had to prove I was a man of action."

The family agreed to meet up for his 21st birthday in November, and to combine it with his father's 50th. "It was a happy but muted occasion," admits William. "So many bridges had been burnt that I knew it would take time for the family to learn to trust me again."

Since then, William has been on ITV with his mother talking about their journey as well as a spokesperson for a Government campaign warning against the effects of cannabis. He speaks to his parents every day, goes to movies with his brothers, and has seen his parents half a dozen times. "It feels good to be back in the fold," he says.

For Debra the overwhelming feeling is one of cautious relief. "I feel like I've got my son back. But we're still taking baby steps in rebuilding trust. We never stopped loving him, only his behaviour was unlovable. But he has shown remarkable strength of character to make this shift and I am very proud that he has done so."

For William, "things are opening up that were unimaginable a year ago," he says. His message to Julie and Jonathan Myerson is to "hang in there. Your son is not lost. He's angry now, but eventually he will take responsibility for his life and come to realise that skunk, not you, is the real enemy."

Parents seeking support can contact Debra's website www.talkingaboutcannabis.com or call 0844-335-1506.

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