Each performance of Dreamtown by Glasgow-based Theatre Works is followed by workshops, bringing the cast into daily contact with young people. “If you go in not knowing what is in ecstasy, or the effects of speed, the kids will just eat you alive,” Catriona MacPhie, Dreamtown’s director, says.

Patrick Evans’s hard-hitting play has been a runaway hit with staff and pupils. Some schools asked the actors back for a second visit. A teenager dies after taking ecstasy and a woman who injects temazepam has a leg amputated. Catriona MacPhie is adamant: “You have got to be upfront, in your face, stop people and make them think.”

“Once the sound of chewing gum stops, you know you’re on a winner,” one actor commented. Most of the cast admit to surprise at how widespread drug abuse is among teenagers. Out of a group of about 20 in a workshop I attended, most had tried hash, about half had taken jellies (temazepam), and a few had tried acid, speed and ecstasy.

Despite the shock tactics, the main aim is to inform rather than simply condemn drug use. “You can’t stop young people experimenting,” Catriona MacPhie says, “but if you give them correct information you are giving them the confidence to make informed choices. It is as much about handling peer pressure as teaching them about drugs.”

One deputy head adds: “The just say no message has limited relevance when so many young people have already said yes.”

The script is constantly updated. It reminds ecstasy users, for example, to drink water to guard against dehydration. But after the death of teenager Leah Betts this section was revised to contain information on dilutional hyponatremia, a dangerous condition resulting from drinking too much water.

“If the music is even slightly out of date, they’ll think you are old fuddy-duddies,” Raymond Young, the sound engineer, says. Few pupils will talk openly about drugs in front of teachers. But the actors quickly win respect and trust.