Paul is one of eight young adults with multiple and sometimes profound handicaps who travel to Stoke Heath Young Offender Institution in Shropshire every week to take part in an unusual arts-based Saturday school. A series of heavy grille doors are opened and, in the education wing of the prison, the group meets up to a dozen inmates, all of whom have volunteered to help.
This week Paul is being looked after by Mark, whose relative cheerfulness may be due to the fact that he's due for release in a few days. Like the others in the classroom, the two of them are working with paint and egg boxes to create a three-dimensional picture of an animal, whose shape has already been outlined on a large sheet of paper.
It's a typical activity for these Saturday mornings. The tasks are invariably very basic and simple - but then they have to be, since all the visitors have severe learning difficulties. Paul, for example, enjoys painting, but has a concentration span of around 30 seconds, and needs a great deal of help and understanding if he is to produce anything other than a mess of paint.
Mark seems able to provide this, guiding Paul to apply the paint carefully, and appearing quite unembarrassed by his frequent loud exclamations, or his determination to kiss his hand at regular intervals. "I get a good feeling when I'm helping people like this," he tells me. "I might get into it seriously one day."
The Saturday school at Stoke Heath has been running for four years, funded at a crucial stage by the Prince's Trust. What began as an informal link between the prison, near Market Drayton, and some severely handicapped teenagers from The Old Barn, a nearby residential home, has become a regular feature in the institutional lives of all concerned.
Inevitably, the benefits come not so much from the end-products of the morning - which are often displayed on the corridor walls - as from the encounter between the two groups of young people, with their contrasting needs and circumstances.
For Paul and the others from the home, it's a chance to broaden their very limited horizons. Aged between 20 and 26, only one in the group, John, is capable of living even semi-independently; the others need constant attention and assistance. Coming to the prison every week helps to break the inevitable isolation they experience in the home.
"This activity and music are the stimuli they enjoy most," says Stephen Briscoe, the team leader who's with them this morning. "They do this kind of activity in the home, but here they're meeting different people. You can tell they enjoy it; they're very disappointed if they can't come one week."
For the inmates, the benefits are of a rather different kind. Stoke Heath, a group of low buildings set in one of the flatter parts of the Shropshire countryside, houses around 300 youngsters aged between 17 and 21, the majority from Liverpool and Manchester. The prison is preparing to take juveniles in the 15 to 17 age-category, and its population is set to rise to 400 this year, and 550 by the end of 1996.
Most of the boys here already seem to have the cards stacked against them. Up to 70 per cent have been in care - one boy has notched up 13 foster homes. Many come from single-parent families. Some from large families have been kicked out of their homes, their parents claiming they can't afford to keep them. Few have had a job.
Their offences are various. Many have stolen cars to sell the parts. Others have offended under the influence of drink or drugs. Petty theft and robbery are common, though the sums are generally small. With some there has been a degree of violence, usually involving a fight in street or club.
"I'm not excusing their offences," says Barry Pierce, a principal officer at Stoke Heath, "but we're looking at the second generation of the jobless. Mentally these boys are quite scarred, and many are unable to express themselves verbally."
Inevitably, most of the boys have been on the wrong side of authority for much of their lives. Suddenly to be put in charge of someone else, however informally, gives them a startling new perspective on their own circumstances.
Martin, an inmate for six months, is one of the more articulate. At first he volunteered simply to get out of his cell. He'd not worked with a handicapped person before, and intially felt awkward. Now he enjoys the challenge. He's working today with Sharon, one of the more able of the visitors, who's nevertheless very nervous and unconfident.
"Working with handicapped people like this makes me realise they can never do what they want," he says. "It makes you appreciate what you've got yourself, what you can do. It also gives you a feeling of freedom, because you've been trusted with people from outside. I think they get enjoyment knowing that people care for them."
One of the purposes of the scheme is to stimulate precisely this kind of reflection. The Saturday school is seen as an important element in the prison's efforts to rehabilitate these youngsters, so they can become more thoughtful as well as law-abiding citizens when they eventually leave Stoke Heath.
John Alldridge, the prison's governor, is clear about the value of the project. "It's often the first time they've been in a situation where things are not their fault. Here they're coming across others who are indisputably worse off than they are. It makes them reassess their view of the world, which they normally see as divided into prey and predators, into them and us. "
The inmates' role in these sessions is to help the visitors in any way necessary. This may vary from simply passing materials or providing a steadying hand, to offering words of encouragement or advice, or accompanying them to the toilet, where they might help to change an incontinence pad.
The inmates do not work unsupervised. The project is run by three teachers from the prison's education department. Today Wendy Sweet and Hilary Bolton are in charge, ensuring everyone has the materials they need, keeping an eye on progress, stimulating conversation - and checking that none of the pairs of scissors walks.
Wendy Sweet says they get all sorts volunteering. "It's surprising how many already had contact with a handicapped person, sometimes in their own family. But some are nervous at the prospect of working with such a group; they come once, and find they can't handle it. Sometimes we get the bullies - but they're just as good at it as the others. I think for all of them, being put in a position of trust raises their self-esteem, and builds up their confidence. "
Such outcomes are not always obvious - but occasionally they may be. One inmate, who was noted for violence and had lost most of his remission, had spent many days in the prison's segregation unit before joining the project. Soon he was telling one of the teachers that he "couldn't go down the block again" because one of the handicapped group "relies on me being here on Saturdays". He was not reported for bad behaviour again.
Hilary Bolton, who teaches the inmates during the week, says: "You see a different side of them on Saturdays; they're not trying to impress each other like they do in their ordinary classes. We get used to the bad language - it's like living near the railway, you don't hear the trains. But we warn them not to use it on Saturdays, and they don't. For them it's like a little playschool, and they get upset if they're not called."
No doubt some inmates volunteer in order to break up their weekend: "I'd be watching television otherwise," one admits. But the fact that many continue to turn up week after week, and see the scheme in positive terms where so much of their lives has been negative, would appear to underline its value.
Allan, who's been inside for 18 months, speaks for several others when he says that all prisons should be running such a scheme. "Most lads here think they're hard done by. But there are people out there who are much worse off."