Most viewed those who fell under the spell of heroin at a safe distance and slept easy in the knowledge that, like the characters in Irvine Welsh's Trainspotting, they belonged to a very different world from the rest of us.

For the middle classes, cannabis was little more than a rite of passage, a novelty which wore off when student days ended. Even those who dabbled in Class A drugs weren't prepared to sacrifice nice cars, their own home and other material comforts for their addiction. Drugs were around, but they didn't intrude on day-to-day life.

However, times have changed. More and more youngsters from families once described as "nice" and "ordinary" are experimenting with drugs, usually cannabis, before they've even decided what GCSEs to take. For some it will be the start of a life-long battle with addiction.

Despite the growing evidence, ignorance remains bliss in many well-heeled communities which are unable to accept a problem once seen as blighting a lost underclass has arrived on their doorstep.

Just last month, Suzanne Knowles attempted to prick the conscience of her neighbours in Harrogate following the death of her son Jake, who hanged himself after a two-year addiction to cocaine. Jake was 14 when he started smoking cannabis, but Suzanne knows that other mothers find it easier to view his death as a tragic but isolated incident, refusing to acknowledge that the town's parks have become a destination for dozens of youngsters unwittingly following in his footsteps.

There has been much debate as to whether cannabis is a gateway drug which leads users towards cocaine and heroin. The arguments on both sides can be persuasive, but after watching her son Matthew change from an outgoing intelligent teenager into a reclusive young man, Lesley Jakeman is in no doubt about the link.

"Some people have a romantacised view of cannabis, but it isn't the same as it was in the 1960s," she says. "Now its incredibly strong, it changes people's personalities and when you start smoking it before your brain has even fully developed who knows what the long term consequences can be."

Matthew, who was smoking cannabis at 15, quickly graduated to heroin and while he had moved out of the spacious family home in a leafy part of York, he remained close to his mother. With her help, he secured a place in rehab, but after being clean for nine months, he met up with a fellow user and the lure of one small hit proved too much. It was to be his last.

"The post mortem showed the level of alcohol and drugs in his body wasn't particularly high," says Lesley, who teaches in North Yorkshire. "The problem was that because he'd been clean for all that time his tolerance was just too low. During the time he was clean I suddenly saw my bright, articulate son return. He'd found a job, he was interested in life again. I really thought he'd cracked it."

Shortly after Matthew's death, Lesley was referred to the Marcus and Luke Trust. The support group was set up by Susan Garner and Marilyn Shaw following the death of their sons in almost identical situations. Like Lesley, Susan and Marilyn are typical middle-class mothers left to deal with the fall-out – and the stigma – of addiction.

"As a parent you're torn," says Marilyn, whose son Marcus died of an accidental overdose when he was 22-years-old. "People suggested trying tough love, but when I threw him out his addiction deepened. I just felt so guilty. We paid for him to go to a clinic in Switzerland and we really thought he'd beaten it, but as soon as he stopped taking the opiate blockers which nullify the effect of heroin, he started again.

"No one sets out to be an addict and I am not ashamed of Marcus, but I am ashamed to live in a society that does not educate people fully in the dangers of drugs, which allows the culture to flourish and which allows music and film icons to be seen and known to take drugs without comeback. "

With clinics like the Priory having become a revolving door for celebrities who want to clean up their act, it has, Lesley believes, given people the wrong impression of just how hard securing a place in a rehabilitation unit can be.

Like Marilyn and Lesley, Susan also had precious moments when she felt her son Luke had turned a corner. However, at the age of 19, he too died of an overdose and his funeral was held on the day that
should have been his first appointment with Harrogate Addiction Team.

"After his death there was a lot of unanswered questions," says Susan. "I wanted to know if I could have handled the situation differently, why there wasn't more help available and why Luke had found it so easy to get hold of drugs. It's so difficult for a parent to stand by and watch their child abuse themselves.
You want to help, but you don't have the support or expertise to do so."

The three women are holding an awareness day in York next week, which they hope will help to expose the problem of drug addiction among ordinary families. The event, which is also being supported by former North Yorkshire drug squad officer Dave Parvin and Government cannabis expert Mary Brett, will pull no punches and hopes to bring a widespread problem into mainstream debate.

"Drugs misuse has no social boundaries and those who abuse drugs are very often the last people you would expect," says Dave, who now runs the training and consultancy business Drug Sense UK. "Having a son or daughter addicted to drugs is any parent's nightmare, but we can't close our eyes to the problem any longer. No one is suggesting drug addiction is an easy thing to stop, it's not, but if we can make parents aware of the signs that their child might be in trouble it has to be a start."

Aside from the stories of Lesley, Marilyn and Susan, the most persuasive call for change will come from Mary Brett, who says scientific evidence debunks any notion of cannabis as a soft drug.

"The legalisation argument has left our children confused and bewildered," says Brett. "There's no point saying to children 'don't do drugs' or 'just say no', but there's every reason to point out biologically what could happen to their brains and their bodies. I add to that all the adverse social consequences and lost educational opportunities and they begin to see the futility of that particular lifestyle.

"Children need rules and regulations. They need boundaries to kick against. It's the only way they feel safe and secure. It's a dangerous
myth that cannabis is harmless, and most users are unaware of its effects, especially on the brain.

"Over the last few years I have met several parents who have lost children to drugs. The one who has made the biggest impact on me is a woman, a writer, now in her early 70s.

"Her son started using cannabis at the age of 15 at his public school. As so often happens, he progressed through all the other drugs and spent the last years of his life in care homes and psychiatric institutions.

"She never gave up on him, but shortly before he died, at the age of 45, of a particularly pure does of heroin, he told her he could handle any drug now, except cannabis. It made him paranoid and terrified.

"Cannabis is a harmful drug, and we must do everything we can to ensure it never becomes legal."

The drug awareness day will take place from 9.30am-2.15pm on Friday, October 17 at Kings Manor, University of York, Exhibition Square.

For information see www.lukeandmarcus
trust.org.uk or call 07793 619312 or 07980 634381.