Clarke Peters, star of cult US crime drama The Wire, talks about hanging up his badge, checking into Holby City and playing Nelson Mandela…

You’re joining the cast of Holby City this week as Donna Jackson’s father. What can you tell us about him?
“He comes in for a check-up and ends up as a patient with major complications. This has an enormous impact on both him and Donna. He’s not a complicated man, but he has complicated emotions.”

What’s it like coming into such a long-running show?
“I thought it would be a lonely experience, as you are joining a functional family of actors and would be just a guest in their house, but the cast and crew welcomed me and made me very comfortable.”

You recently played Nelson Mandela in the Channel 4 drama Endgame. Can you ever top that role?
“There are so many people of African descent who are yet to be rediscovered and revealed – the Haitian revolutionary leader Toussant L’Ouverture, for one. How important is he to world history? Yet he hasn’t been touched.”

You’ve been in two of the best US series of recent years: The Wire and Damages. What makes them so special?
“The Wire is special because it doesn’t dumb down. It demands your attention and rewards your efforts to stay with it, like a well-written book. Damages is The Wire of the corporate world.”

How hard was it to say goodbye to The Wire’s Detective Lester Freamon after six years?
“I’m not sure I’ve said goodbye to Lester; the success of The Wire has left him lingering. In light of all the financial corruption being exposed in England and the States, I’ve been tempted to have T-shirts printed with: ‘Freamon would have figured this s**t out by now… follow the money!’”

You write as well as act. Do you have a preference?
“I like doing them both. Writing helps me explore the stories within, acting allows me to tell them, whether they are mine or not.”

If you could change one thing in the world, what would it be?
“The air and the water need to be purified of pollutants that cause all of us harm.”