The perks are impressive: a generous salary, flexible holidays and a decent pension scheme. But, as always, there’s a catch: the pupils include England’s youngest perpetrators of violent crime.

Almost 300 children aged 12-17 are locked up in four secure training centres (STCs) around the country. They are schooled in secure rooms, are accompanied by prison guards and need permission from the Home Office to go on field trips.

Many have had horrific life experiences and most have committed truly terrible crimes. In other words, a child who winds up in an STC brings large quantities of emotional baggage with them.

The world of an STC teacher might seem strange to teachers used to mainstream schools with mainstream children. And yet there is much shared territory. Pupils must acquire skills and opportunities that will be of value in adult life (although some may have to wait as long as 15 years to use them). Their “school” follows the national curriculum and there are strict rules on uniform.

For those who choose to work in a secure environment, there are marked attractions that sit alongside the more obvious challenges. Staff are quick to point to the enormous leaps forward a young offender can make while in custody.

Take, for example, the double murderer with a serious self-harming habit who now works happily in lessons, the robber learning to become a painter and decorator, and the teenage sex offender proudly studying for his GCSEs. These are not isolated incidents.

Life for the institutions and their staff is not simple. In 2007, for example, just three years after Oakhill STC in Milton Keynes opened, prison inspectors said staff struggled to maintain order and control children safely. They had an “embattled and reactive” approach and there was a disproportionate use of physical restraint. In just nine months, staff used force 757 times. On 532 occasions this involved at least three members of staff.

As a result, the Youth Justice Board (YJB), which oversees, commissions and regulates the private firms that run the STCs day to day, limited the number of children at the centre, which was temporarily closed in 2008. The contractor, G4S, produced a recovery plan.

Inspectors said the task was “immense”. But last year Oakhill was rated outstanding by Ofsted, as was Rainsbrook in Northamptonshire. Medway in Kent was “good” while Hassockfield in County Durham was deemed satisfactory.

But while things are largely looking up for the tight-knit STC community, the future is uncertain. The YJB is in the long queue of organisations waiting to be thrown on the Government’s bonfire of the quangos. Its duties will be absorbed by the Ministry of Justice. Ministers have promised a reform programme that will “improve rehabilitation; prevent youth crime and cut re-offending”. Details, however, are scarce.

But visitors to STCs will find little outward sign of worries about the future. Teachers at Oakhill and Rainsbrook strive to keep the school environment similar to the “real” thing. Resources and equipment are largely on a par with those found in schools throughout England.

There are courses in hair and beauty, with a salon to practise in. Pupils can study construction, and their efforts at building walls and laying patios can be seen in the grounds. They also learn painting and decorating, demonstrating their skills in a spare room. Humour is a frequent presence: pupils jokily ask visitors to secure their early release.

One of Oakhill’s 15-year-old inmates, serving time for robbery and aggravated burglary, has mastered the art of wallpaper hanging. “I thought I was just going to be locked up, but we’ve been able to choose from different options and learn about different careers,” he says. “I used to go to college, and I want to go back when I’m released.”

Other children are simply pleased to be able to continue the academic work they were doing at school. “I was able to take GCSEs early, I didn’t do as badly as I expected and now I’m taking more,” says one teenage boy.

“Education has helped us a lot to cope with being in here. We also get access to the gym and salon, which is great.”

The school day begins with a meeting between children and care staff. Teachers are told by staff if a pupil needs special attention - they might have had a distressing phone call or a meeting with their solicitor.

Classes start at 8.45am. There are four 45-minute lessons, followed by a two-hour break and two more 45-minute lessons. This regime lasts for 52 weeks a year - keeping these children unoccupied for six hot weeks over the summer is clearly not an option. At the end of the school day, teaching staff formally hand the children back to care staff.

It is considered important that classrooms are separate from the living blocks, where children are housed in groups of eight. School staff are banned from seeing the bedrooms, heartbreakingly neat and tidy, with pictures of family and friends and posters for good achievement proudly displayed.

“There’s a real shared approach among teachers, and an awful lot of humour,” says Tom Durnin, former assistant head in a mainstream school and now director of education for G4S, which runs Medway and Rainsbrook as well as Oakhill.

“We have to raise children’s self-esteem and confidence, but this is not easy. Our pupils come from all around the country and are any age from 12 to 18. They are at all stages of educational experience and ability.

“It’s very challenging. The only time we don’t teach is at weekends and bank holidays.”

On pupils’ arrival, staff assess reading age, educational history and try to discover which is their best “learning style”. Each child has three support staff: a case manager, a key worker and an educational tutor, who liaise with their former school. Those who have been studying for GCSEs are encouraged to take their exams. Children with special educational needs statements or learning difficulties receive one-to-one lessons, and support in class from a teaching assistant, just as they would “outside”.

All are set individual targets for maths, IT, English and independent living. They are obliged to sign an educational contract, which sets out what teachers expect from them.

“At first many children are shocked; they think prison is going to be a free for all,” Mr Durnin says. “We try and give them a taste of the real world, too. They learn practical skills, in the hope they will be employable on their release.

“But the emphasis is also on academic subjects,” he adds. “For example, we run French (classes). Everyone thought we were mad but the children love it.”

Teachers meet daily to review the progress of pupils. All teachers at Oakhill and Rainsbrook have previously worked in mainstream schools. They get the standard 12 weeks’ holiday a year, but have to make sure their lessons are covered in their absence, providing lesson plans for their colleagues.

“A lot of our staff were attracted by the flexible holidays,” Mr Durnin says. “They are very attracted by the fact they can have days off.” One staff member even joined from top independent school Rugby.

Good behaviour in class is rewarded with points. And points means privileges - for example, their own TV.

Most children are kept in STCs for between four and 24 months. Those with longer sentences transfer to an adult jail when they turn 18.

Staff have to adapt to the different kinds of criminals who come through the centre’s doors.

“When I started my career, common offences were car stealing or glue sniffing,” says Paul Cook, managing director of children’s services for G4S. “But now many crimes are committed in gangs, most are alcohol fuelled. There are more street robberies and house burglaries, with the child stealing small items.

“Offences are much more violent. But claims that many involve drugs are wrong - often our children have dabbled, but they are not addicted and we rarely have to put them on a detox programme.”

Many of the STC charges were in care and committed their offences while in children’s homes or living with foster parents. Those with families are encouraged to have visits from their parents.

“We try to build bridges,” Mr Cook says. “Often for the families it’s the first time they have heard something positive about their child.”

Graham Robb, YJB member and former headteacher, says the work of teachers at the centres is “critical”. “It’s essential we help these children start learning so they don’t re-offend when they leave,” he says. “But most have had a rotten experience in the classroom up until the time when they get to a centre.”

Mr Robb says co-operation with mainstream heads is a major headache. “I am constantly pleading with schools to accept children back,” he says. “Being back in a school helps the child settle back into the community, helps them continue their good habits. But too few get this opportunity for full-time education.”

Only hardened members of the “hang `em and flog `em” brigade could question the value of these institutions and their skill at creating educational opportunity for children in the most desperate of circumstances. The men from the ministry are surely acquiring a prize asset.