Mrs Blair tried on headphones during a tour of the studio

The prime minister's wife was shown around the new studio at Wandsworth Prison by Gavin, 22, who is serving five years for possessing firearms.

Inmates at the prison will run "Radio Wanno", thought to be the first talk-based radio network in a UK prison.

Ms Booth QC said it was a "fantastic and imaginative idea" which could be a model for other prisons if successful.

She said it would "provide prisoners with vocational skills and qualifications but also makes the link between prison education and employment on release".

The station will broadcast on 999 AM for an hour every day from a specially-built studio within the jail.

I have worked on radio stations before - mainly pirate ones Foxy, inmate

Prisoners involved will work towards qualifications in radio production skills, which could see them end up on mainstream radio stations.

The idea is to show inmates how to get an education, stay off drugs to turn them away from a life of crime.

They want to tackle issues like inmates' attitudes towards their victims and how they will deal with life after their sentence.

One inmate Foxy, 36, doing three years for assault and theft, said: "We are trying to restore people's self-worth.

"I have worked on radio stations before, mainly pirate ones.

"My ultimate ambition is to get contacts and work with a commercial radio station and show myself and family and others that I can work and have a productive life."

The Paul Hamlyn Foundation and the Esmee Fairbairn Foundation, who are funding the scheme, hope to extend it to other prisons.