His parents had thought it was the au pair who was smoking in the house when Jake began using cannabis at the age of 15. "We thought we were ready for a bit of pot," said John. "Our daughter came back from a party and was really ill from it when she was 15 and we teased her about it – of course, she never touched it again. I smoked at university, we all did, and always envisaged how I'd tackle it chummily with my kids, play the cool dad. God, how stupid. This stuff is not the same ballgame."
Then came the school truancy and the stealing. "All for a drug they try to tell us isn't addictive," said Susanne. "His life is disintegrating before our eyes."
Debra Bell will use her real name. From south London, her son William is now 21 and also through the worst of what she believes was a skunk addiction that turned a sporty public schoolboy into a violent, aggressive thief.
"We knew about cannabis, but nothing about skunk. It was all such a shock," she said.
"We were undermined as parents, by the government downgrading it, by doctors not taking it seriously. William could just shrug his shoulders and say everybody at school was doing it, and it was pretty obvious in the months that followed that they were.
"My husband is a barrister and he started to see that this was a drug addiction. He began to wash his hands of him, but this was my beautiful boy… we fell out a lot over it. Guy's stance was tough and eventually we did throw him out of the house and I didn't see him for a year. It was a nightmare."
All her efforts to get help foundered. "The professionals were just out of date in their understanding. We felt deeply ashamed that we couldn't get a good outcome for our son, as he was sliding more and more into this nightmare."
Now reconciled with William, Bell set up her own website in the end and found a flood of other families desperate for such a helpline. "Suddenly we were just hearing all these carbon-copy stories, thousands. It is such a hidden subject, but such a huge phenomenon. No respect for class or creed or colour. I think we have betrayed our children through our ignorance. Our generation smoked, but here and there. Everybody did it – but children didn't smoke it, children whose brains were still developing."
