Sylvia is the cynic in the officers' mess - the epitome of the 'never listened, never learned officer'. She despises Helen as a prisoners' friend. She always thinks the worst of people and their motives and no matter what, always feels hard done by. She moans constantly about her job and the prisoners whom she hates, but the truth is, she loves coming to work and bad-mouthing folk.

Helen Fraser is a million miles away from Sylvia Hollamby. And Sylvia Hollamby is a very different character to anything that Helen has played before. But the celebrated actress has certainly enjoyed getting her teeth into Sylvia.

"I have really enjoyed playing her. She isn't like me at all. She is very old school and mean to the people she is in charge of and she is not going to get on with Helen Stewart at all.

"Sylvia is a very settled prison officer and doesn't like any changes. She is only working to supply everything she wants in her retirement. Ideally she would like all the prisoners to be banged up 23 hours a day. She believes that people who have committed a crime should be well and truly punished. And so as she thinks like that, I've deliberately made her very unglamorous."

Helen knows that Sylvia's job is not something she could do. "I couldn't do this at all. It even upsets me being in our prison set. I can't stand the thought of being shut in and not being allowed to go out in the fresh air."

Although filming inside a prison has changed Helen. "I have really enjoyed it, but I do now dread being locked up more than I used to. I now make sure that I don't drive my car too fast or break any laws because I never want to find myself in that situation."