Jailhouse shock: Schoolchildren are given lesson on grim reality of life behind bars

Juvenile offending: Inmates warn pupils about the violence, squalor and boredom inside to help destroy macho myths

Chris is serving life for murder. He has just told the tale of how he seized "the biggest two knives I could find" and stabbed his victim to death. Then he notices a teenage schoolgirl apparently giggling with her hand before her face.

Chris is serving life for murder. He has just told the tale of how he seized "the biggest two knives I could find" and stabbed his victim to death. Then he notices a teenage schoolgirl apparently giggling with her hand before her face.

"You think it's funny - me having killed someone?" he asked. Then he realised his mistake. "I thought you were laughing, now I can see you are crying. I don't know what to say."

The tearful 15-year-old was among a room of young people brought into one of Britain's most notorious jails last week to meet inmates and get a taste of real prison life.

The visit is part of a new programme, in which the Prison Service has consented to allowing parties of schoolchildren as young as 13 into prison in the hope that they will be dissuaded from returning as prisoners.

Inside the walls of Wormwood Scrubs, west London, the children listened in awe as two killers and three drug dealers described their daily existence inside the prison.

They talked of attacks on the landings with boiling water mixed with burning hot sugar and of weapons fashioned from shaving brushes and razor blades. Most of all they told of the crushing boredom and loss of dignity, locked up for 23 hours a day and eating their meals alongside the stench of their cell lavatory.

A prison officer brought forward a metal tray of typical Scrubs fare - a scoop of yellowing mashed potato, some stringy green beans and a brown gloop described as "today's Halal meal".

The children were thrown a pair of standard issue wash-and-reuse prison underpants and asked how they would feel about "wearing other people's underwear".

Finally they were taken to a cell to feel the closeness of the grey walls and to hear the door clang shut behind them. For the children, it was a far cry from the boastful stories related by "friends of friends" about prison being "easy".

News of the Wormwood Scrubs scheme has spread rapidly through the education system as teachers have seen how the experience has influenced youngsters.

Last week children travelled more than 70 miles from Gosport in Hampshire to meet the likes of Chris, the killer, and Don, a drugs dealer. The prisoners described their damaged lives with a candour that dispelled any notions of a school trip to the Chamber of Horrors.

Linda Alderson, an education worker at Hampshire County Council, who accompanied a party of children who had been excluded from school, said: "We want the kids to see the reality of prison; that it's not glamorous. So many of them have that view. Men come out [of jail] very macho saying, 'It's OK' and that is what the kids hear."

The message seemed to have got through to one boy, Paul, aged 15, who said he did not recognise the austerity of the Scrubs regime from the picture of prison painted by friends in Gosport.

"It hit me a bit," he said. "You are told when to get up, when to sleep, when to exercise. And the people we were talking to - they did not look like anything. They had glasses on. It showed me that anyone could be a murderer."

Most of the youngsters visiting the prison are ordinary schoolchildren, with no past record of criminal behaviour.

Elsa, 15, from Queen's Park Community School in west London, had earlier cried at Chris's life story. She said: "I know people who have been in prison - the so-called bad boys. They say it's easy. Butwe are seeing a different side of it from people who are spending their whole lives in here."

The Wormwood Scrubs scheme, called Prisoners Against Youth Drug Abuse, aims to emphasise the links between drugs and crime and is driven by the desire of inmates to warn youngsters against making the same mistakes.

Chris and Winston blamed drugs for creating situations where they armed themselves with a knife for protection and killed someone with a single stab wound. Children who visited the prison have written to say they no longer carry knives after realising the possible consequences.

Many of the visitors take the opportunity to ask prisoners questions. Peter, a drug dealer serving seven years, said: "You can tell they are talking about themselves but they are saying, 'I know somebody who started dabbling in something'. We try to be as honest with them as possible."

John Hancock, the prison officer who set up the programme, said: "Children at school are told by teachers, doctors and police officers to stay away from drugs but to hear it from a prisoner's mouth can be much more effective."

It is a view the children seem to share. At the end of one visit, a girl told the prisoners: "I just wanted to say that you are all brave for what you have done. It's been good for me."