Ronnie Thompson was a prison officer who helped to stop riots and outbreaks of unrest but he left his job after becoming disillusioned. He has since written three books including a new novel about a young offender.
He talks to Jonathan Charles about why he believes there are big problems with the way that Britain's jails are run.
You can watch the full interview on Tuesday 4 January 2011 on BBC World News at 0430, 0930, 1530 & 2130 GMT and on BBC News at 0230, 0430 and 2330.
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