Steve Taylor admits that, before he was jailed, he was the "most right-wing reactionary person you could find".
Four months behind bars transformed him. Appalled by the "pointless warehousing of people" that he encountered, he came out dedicated to improving the lot of inmates.
"The bubble had been burst. I had seen the waste of prison, but I had also seen the potential for prison," said Mr Taylor.
After gaining a university degree, he became involved in a project dedicated to driving up standards of education in jails.
For his efforts in forcing an unfashionable subject into the limelight, Mr Taylor will be awarded the Longford Prize today.
The award, sponsored by The Independent and named after Lord Longford, the penal and social reformer who died in 2001, recognises "outstanding qualities of humanity, courage, persistence and originality".
During the two years that Mr Tayor has headed the Forum on Prisoner Education pressure group, he has appeared regularly in the media, given evidence to Parliament and produced a widely praised report calling for inmates to receive unrestricted access to the internet.
In addition, he tours jails giving practical advice to inmates on gaining qualifications as a route out of crime.
Mr Taylor, 29, who declines to discuss why he was jailed, said: "It's important to me that we spend as much time as possible talking to people on the ground to see what we can do to help. I have to make sure we're in the real world. I can't be bothered with hypothetical carrying-on about abstract issues."
One of the people who nominated him, a former prisoner now working as a baker after obtaining a BTEC vocational qualification, said: "If Steve hadn't got involved, I wouldn't have my qualification. Steve really helped me and made a difference to my time in prison when he didn't have to."
The forum's chairman, Professor David Wilson, said: "Steve's commitment, organisation, passion and understanding stem from his direct experience of imprisonment and his desire to reform the circumstances he encountered while banged up."
Two other people were also highly commended by the Longford judges. Marian Liebmann, from Bristol, was recognised for her pioneering work with prisoners on art therapy and restorative justice - bringing offenders and their victims together. Liz Hoyle, from Keighley, West Yorkshire, the founder of a worldwide network linking prisoners writing poetry, is posthumously recognised. She died of cancer this year but her organisation continues to flourish.
The winner last year was Christopher Morgan, the founder of the Shannon Trust, a charity dedicated to tackling illiteracy in jails by encouraging educated prisoners to coach their cellmates.Reuse content