What does a young troublemaker look like? There are plenty of stereotypes to choose from - crop-haired corner boys on rundown estates, streetwise girls acting hard in suburban shopping malls, tough little knuckle-duster faces on late-night buses, playground gangsters at the school gates. These are the figures of popular fear and urban myth, the out-of-control youths who fill newspaper columns, running riot in the classroom and terrorising teachers. The fear and loathing prompted by disruptive teenagers reflects the anger and powerlessness that adults feel towards children who won’t behave. But when you meet these demonised youngsters you find a more complex story.

The Zacchaeus Centre, in Birmingham’s city centre, works with young people who have behavioural problems, drawing its pupils and part of its funding from the city’s Roman Catholic secondary schools. Here, in an attempt to break a cycle of disruption and punishment, children are taught for one month in small groups, in an environment designed to prevent habitual anti-social behaviour.

When the Daily Telegraph reported on the centre’s opening last autumn, the headline promised “Catholics to open a boot camp for young rebels”. But when you step inside, neither the institution nor the “young rebels” match expectations.

They might only be first impressions, but what you see at the Zacchaeus Centre are subdued and self-absorbed children, looking as though they’ve had a lot of practice with bad news. There are jumpily aggressive children, ill at ease with themselves, accustomed to using attack as the best means of defence. In a few faces there is a discernible sense of emotional remoteness, as though they were looking at the world around them from somewhere a long way away. The overall effect is one of inadequacy rather than malice.

The term “boot camp” also is misleading, suggesting parade grounds and sergeant-major psychology, where young thugs are cold-showered into submission. Instead, the Zacchaeus Centre is more interested in pastoral care than punishment, with the goal of returning children to their own schools in a frame of mind which will allow them to improve their behaviour.

Moyra Healy, head of the Zacchaeus Centre, says that the purpose of the project has been to provide a distinctly Catholic response to the needs of difficult children. “There is an excellent behaviour-support service in Birmingham, but there wasn’t any specific place for pupils from Catholic schools.” This meant, in practice, that disruptive children were not only being thrown out of their schools, but out of the whole Catholic education system. “We were rejecting our children and they must have felt as though they were no longer good enough to stay in our schools.”

This, Moyra Healy says, rested uneasily with a Christian commitment to forgiveness and compassion. As such, a partnership of Birmingham’s 10 Roman Catholic secondary schools decided to open their own behavioural therapy centre, under the aegis of the city’s Behaviour Support Service. Funding for two staff was provided by Birmingham local education authority, and Moyra Healy, head of RE at one of the partner schools, was retrained to be head of the new centre.

Now beginning its third term, the Zacchaeus Centre takes groups of up to 10 students, between the ages of 11 and 14, with each of the partner schools allowed one place per month (the schools pay an annual fee of Pounds 450 plus Pounds 75 per student per month).

As much of the curriculum as is practically possible is taught, but within the context of two strongly apparent themes - pupil behaviour and Christianity. In the corner of the classroom is an altar and a small, makeshift chapel, where each day begins with an assembly and prayers. Although Catholicism might be expected to specialise in guilt and sin, Moyra Healy says that the emphasis is on reconciliation and redemption.

“The whole ethos is forgiveness,” she says. “It’s about the need to know that you can be forgiven. The children come here with a great sense of being unforgivable. I have always found that children, especially those written off by the great majority, have a deep inner awareness. They are often harder on themselves than anyone else.”

The centre’s name also reflects the emphasis on redemption, taken from Zacchaeus, the outcast tax collector forgiven by Jesus. Although forgiveness is being preached, there is a clear sense of discipline, with firm rules on uniform and behaviour. On the classroom walls, alongside work produced by pupils, there are the lists of regulations, such as “be prepared to begin work promptly”, “work hard”, “listen to the teacher”, “raise your hand to speak” and “do not distract others in any way”.

The intention, says Moyra Healy, is to offer positive discipline, a blend of strictness and generosity, in which students can be rewarded for behaving with consideration towards others. For many of these young people, trapped in conflict at school and home, the benevolent discipline of the centre offers a sense of security, one of the few places “in which they can feel safe”.

Given that these students have been labelled as being among the most disruptive in Birmingham, the atmosphere in the classroom is striking in its calmness. Apart from being a tribute to the teachers, this air of attentiveness also reflects the intensive monitoring of behaviour. Every pupil is graded for standards of behaviour on a scale of one to five in every lesson, with the figures being added up to a percentage at the end of the week.

This points system, you might think, would cut little ice with hard-nosed lesson disrupters. But when you talk to the students, they provide a blizzard of statistics about their points totals, which in turn are converted into bronze, silver, gold and platinum certificates. The children’s enthusiasm, Moyra Healy says, is because they have rarely been congratulated on anything before.

As well as receiving recognition for their behaviour, the pupils are also made to think more deeply about their actions. At the end of each day, the group gathers with their teachers in “circle time”, when the pupils discuss their successes and failures. In these sessions, Moyra Healy says, “all sorts of emotions can come tumbling out”. In their written work, the pupils are also encouraged to become more self-aware. A boy’s poem gives an insight into how bad behaviour can become a pattern for getting rewards: “When I’m sad or maybe bad My mum gives me money and then I’m glad”.

The question that is most relevant to ask about the Zacchaeus Centre is also the hardest to answer. Does it work? Within these reassuring walls, with two highly-motivated teachers to ten pupils, you can see children working quietly, getting as much attention as they need. But when they return to their own schools, in overcrowded classrooms, where they have reputations as bullies or temper-merchants, it won’t be as easy.

Moyra Healy is the first to say that there are no easy answers in changing behaviour, not least because there are so many different factors involved - anything from difficulties at home to clashes with individual teachers. The children themselves, coming to the end of their month at the centre, seem full of optimism. A 13-year-old girl, who says that she’s been suspended four times in three years for fighting and losing her temper, promises that there will be “a new beginning”.

Full of pride at a series of excellent point scores, she plans to take back her written work from the centre to show teachers in her own school what she has achieved. Articulate and still open to change, you realise how different her future could be. At school she says she has been in constant trouble, told by her teachers that she is “a nasty little liar”. At home there have been violent rows. When suspended, she has hung around the city centre, flirting with danger in the outside world. It doesn’t take too great an effort of imagination to think what could happen next.

The Zacchaeus Centre can act as a temporary sanctuary for this girl and her fellow pupils, but their old lives will still be there waiting for them. The hope of the Zacchaeus Centre is that enough light will have been shed for the pupils to see another, more fruitful, way of approaching their embattled young lives.