The lessons involve looking at plastic replicas of illegal drugs so the parents will know what they look like and how they are taken. Alcohol, tobacco and solvents are also covered.

The London borough of Camden is one of the education authorities running the drugs awareness scheme, which is financed partly by the council and partly by the Department for Education.

All schools wanting to take part in drugs education for pupils were asked to provide classes for parents and governors too.

Camden's Personal, Social and Health Education Officer, Gill Morris, said that as much as anything it was about teaching parents how to broach the subject with their children.

"We feel that the work with parents is useful in terms of educating them about drugs and getting them to talk to their children more openly," she said.

'Don't lecture'

"Parents feel they don't know very much and don't know how to approach the subject of talking about drugs, and we are saying you don't need to 'have a talk' - just pick the moments that you feel would be useful.

'Chasing the dragon'

"The 'lecture' on drugs in response to a situation that has occurred locally or a newspaper article or something isn't the best way - the sort of knee-jerk thing."

The danger in over-reacting to, say, finding cigarette papers in a child's bedroom is that children may be fearful of coming to talk to their parents when they have a problem, she said.

Much of the workshop for parents involves getting them to discuss dilemmas, often arising from very ordinary-seeming events - such as taking their child to the party of a friend and finding that alcohol is available, because that family has different attitudes to such things. What do you do?

Another scenario might involve a young child opening lots of bottles under the kitchen sink and sniffing them, initially out of curiosity.

Reassured

"It is alcohol, tobacco and solvents that most children are going to come across," Ms Morris said.

"Also parents have to realise that they are not alone. Sometimes they feel they are the only ones who don't know what's going on and they are reassured to find that they all feel the same."

Similar scenarios are presented to older primary school pupils in the workshops for schools. One might involve finding a box of brightly coloured tablets with a group of friends, one of whom says: "Let's try some."