In an interview with "Entertainment Weekly" ahead of Comic-Con, the Moff has opened up a bit about the Anniversary, the search for a new Doctor, Matt leaving and the Christmas episode amongst other things.
With regard to Christmas and the new Doctor, he appears to have put a nail in the coffin of the rumours that Matt will regenerate at the beginning of the Christmas episode:
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. The last time, when we chose Matt, we had to hold over on that one, because there was a Christmas Doctor Whospecial called “The Next Doctor” for which Russell (T. Davies, formerDoctor Who showrunner) was playing the game of pretending it was going to be David Morrissey. So we couldn’t deflate that. [Laughs]. But I think we’ll go public pretty fast.
I’m not going to comment at all on the direction we’re going. Sorry!
Yes. That’s not the hope — that’s the plan. 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. [Laughs]
We’re sprinkling fertilizer on his head as we speak. I don’t know. If you care to take a look at “The Angels Take Manhattan” there are a couple of scenes that Karen Gillan came back to do in the graveyard after she’d had her radical haircut and she is wearing what seems like a strategically draped otter on her head. [Laughs]However, we effect it, the Doctor will turn up in his trademark quaff. We can’t have Matt’s last stand in the TARDIS without his proper look. So, thank you, Ryan Gosling…Regarding Matt leaving, the Moff said that Matt had come very close to doing another series:
When did he actually tell you that he was leaving?
We discussed ages ago that we would do three series and then he would do the 50 and then he’d do Christmas. That was Plan A for a very, very long while. That may sound cold that it was so far in advance but you’ve got to plan a career. [Laughs] The question was, “Will I be able to talk him out of it?” We went out for lunch and he said that he’d come very close to doing another series but it was the same argument: “If I do another series, I think I might do two more series, or three more series. I think I might never leave.” It’s that thing of wanting to leave while you’re a huge hit and not let it tail off. It’s part of the ecology of the program, it’s part of the DNA of the program, that there is going to be a new Doctor now and then.None of them ever want to outstay their welcome, and Matt certainly didn’t. Not that I think he was in any danger of that, frankly. It’s also, it has to be said, an overwhelming schedule for the actor playing the Doctor. As a workload it precludes you doing anything else. It precludes theatre, it precludes any significant other television or film work really. And even trying to crowbar some time in for him to do other things — which was part of our charm offensive — in the end he wanted to go and develop the other parts of his career.For the Anniversary episode, you can forget 45 minutes:
What can you tell us about this November’s Doctor Who 50 anniversary show?
[Laughs] Oh, well, very, very little. It will feature of course Matt and Jenna Coleman, but in addition there’ll be Billie Piper and David Tennant and John Hurt. But we’ve been really quite careful. We have a philosophy that anything we shot outside we had to own up to but the rest of it…You’re just going to have to wait until November to find out about.
It’s a special episode. I think you could call it movie-length, yeah. I mean, I’m saying that with a slight hint of vagueness because I don’t know the finished running time. [Laughs] It’s certainly well over an hour.Interesting stuff - you can read the full interview at "Entertainment Weekly".