Porridge star Ronnie Barker has recorded messages for new inmates at Pentonville Prison, London, giving them practical advice on life inside.
Barker is also returning for a Christmas TV special
The actor, who played Norman Stanley Fletcher in the 1970s prison sitcom, will be heard when inmates use a touch-screen information system.
"You must be new round here. The name's Fletcher. Fletch for short," he begins.
A Home Office spokesman said the system was designed to free up staff and introduce inmates to new technology.
"Ronnie Barker is simply providing the voice to provide the information which is vital that prisoners get when they enter a prison establishment," the spokesman said.
In the message, Barker continues: "I've been asked to introduce this here information centre to you on account of the fact that I've had some experience of being an involuntary guest of Her Majesty.
"The first nights would have been easier if I'd had some idea what to expect - what prison life was like."
It is not the only time Barker has reprised his Fletcher role recently - he has also filmed a small scene for a Christmas TV special.
The Life Beyond the Box show, to be screened on BBC Two, will catch up with what Fletcher has been doing in the 25 years since the show ended.