"I love this show, but I've never done anything where you turn up every day for ten months," says Capaldi in the new issue of Radio Times magazine. "I want to always be giving it my best and I don't think if I stayed on I'd be able to do that. I can't think of another way to say, 'This could be the end of civilisation as we know it.'"

"With episodic television of any genre, the audience wants the same thing all the time," he says. "But the instinct that leads the actor is not about being in a groove."
Read the full interview with Peter Capaldi – as well as his co-star Michelle Gomez and Doctor Who showrunner Steven Moffat – in the new issue of Radio Times magazine, on sale from Tuesday in shops.
Via Radio Times