IT could almost be a student hall of residence, with its little communal lounges and kitchens, brightly-painted walls, and rooms decorated with posters of bands and Buffy the Vampire Slayer.

The give-away that you are inside a prison for persistent young offenders is the blue metal door on each bedroom. These doors remain locked from 9.30pm to 7.30am.

Rainsbrook secure training centre is one of three privately-run prisons for 12 to 16-year-olds. The centres have suffered from a poor reputation since the first, Medway in Kent, opened in 1998 and was the site of rioting and several assaults on staff.

Failure to meet targets has also cost the private contractors which run the three existing centres more than pound;1 million in fines. And in October the Home Office said it had abandoned plans to build more units for financial reasons.

But this week the Youth Justice Board announced it would be doubling the number of the centres after inspectors praised Rainsbrook, near Rugby, for its high-quality teaching.

Rainsbrook, which is managed by the Group 4 subsidiary Rebound, has been open for three years.

It caters for 76 boy and girl inmates - referred to as “trainees” - who are placed in flats with up to five others. The young people live, eat and attend classes only with their flatmates. Lessons are organised by City College Manchester and are held every weekday apart from Christmas. Pupils also receive an hour of crime-avoidance training every evening and extra tuition.

Charlotte,16, said she panicked when she heard she would not even get a break during the holidays. Like 94 per cent of Rainsbrook’s trainees, she had not previously attended school regularly. “I thought they were joking,” she said. “But it wasn’t that hard because we get a lot of attention.”

The Office for Standards in Education found that 80 per cent of teaching was good. Inspectors praised Rainsbrook’s 24 teachers for their sensitivity and the “positive and fruitful atmosphere”.

Any problems tended to relate to security measures: pupils often arrived at lessons late because they needed to be escorted by wardens, and most classrooms had a limited layout because the metal chairs and desks are bolted to the floor.

Lord Warner, chairman of the YJB, said: “Few of us like the idea of locking up children, but Rainsbrook is showing how it can be a positive experience.”

In addition to the centres in Rugby, Kent and County Durham, the board plans to open them in Milton Keynes, Essex and Wales.