The writer told Entertainment Weekly: “There’s a very big range of people who could play it and different ways you could go with it. We must get this right. One false move and the show’s over.”

Moffat continued: “Unless we have an insane plan, we’ll announce a new Doctor within days of finalizing the new Doctor. Because it’s very very hard to keep any kind of a secret … I think we’ll go public pretty fast.”

On the subject of the regeneration in this year’s Christmas special, he teased: “It’ll be the traditional regeneration. You know, the eleventh will fall and the twelfth shall rise. And you’ll see that in the closing moments of the show. I mean, you sometimes sit and think, “Are there better ways of doing it? Is there a different way of doing it?” But quite honestly what could be better than that? It’s just too exciting.”

> Find out all the latest details in our Series 8 news summary.

Who do you want to play the Twelfth Doctor? Let us know below…

> Buy Series 7 Part 2 on DVD on Amazon.

> Buy Series 7 Part 1 on DVD on Amazon.

Watch the Series 7 Part 2 trailer…