Jenna Coleman has described Matt Smith’s final episode this Christmas as “perfect” but warned it will be a sombre affair.

Coleman told the Guardian: “I was an absolute mess, an absolute wreck. But it’s good; it’s sad, but it’s what needs to happen. It’s perfect.”

Coleman admitted she held back from reading the script as long as possible: “I’d been putting it off for ages and ages, because once you read the last page, that’s it, the story is over. So I read 10 pages on the tube and I stopped, and then I picked it up again the other day and finished it.”

She also spoke about Peter Capaldi’s casting: “They told me and Matt when Prince Charles and Camilla came to the set. We were both: ‘Ahhh, of course.’ It takes you a few moments – I don’t think he was on any of the original lists. People were talking about Rory Kinnear and people like that, but as soon as you say it, you’re like: ‘Of course.’ As Steven Moffat said: ‘He’s the Doctor.’ And it’s brilliant that we’ve gone so different from Matt.”