What can you tell us about your episode of Doctor Who?
"Bizarrely I think my episode is probably the most reported one! It's set in a spooky hotel. The rooms are full of people's nightmares. David Walliams is in it, wearing prosthetics, and playing an alien called Gibbis. There's lots of running down corridors! It's hopefully a very creepy episode. I got an e-mail from Steven Moffat the other day saying that he's absolutely thrilled with it. I haven't seen the finished cut myself yet, but I've seen lots of the rushes and it looks absolutely fantastic. I think weirdly mine is less shrouded in secrecy than a lot of the others. I seem to be reading a lot about my episode on the various websites!"
What hints can you give about the title 'The God Complex'?
"It's ever so clever! That's all I can say!"
"Yeah, I think so. I think that Doctor Who is an unbelievably difficult show to write, but the rewards of it are immense. It is a really tricky show to write because it demands such incredible momentum and pace, and tonally it's obviously very different to something like Being Human. But that said, I think that the reason this latest episode is the one I'm most pleased with is because tonally it's much darker than 'School Reunion' or 'Vampires of Venice'. That's a tone I'm much more comfortable writing in."
Speaking of tone, how do you respond to comments that the second series of Being Human was too dark?
"I don't think that tonally series two was much darker than series one, and it's certainly not darker than series three. I think that the mistake we made with series two was that we separated the regular characters too much. There's a scene in episode three of series two where they have this big ridiculous argument about The Real Hustle. People pick up on that scene as one that they really like. It's a really funny scene, but I think part of the reason that people love it is because it's the three characters, in a room, having a funny conversation. That's the thing that we didn't have enough of in series two. I don't think that the tone of the Kemp and Jaggat story was much darker than Herrick's story [in series one] or the wolf-shaped bullet [arc]. I think what we lost was the sense of camaraderie, which is hopefully something that we got back in series three."
With series three, how far ahead did you know that you would definitely be writing out Mitchell?
"Not very far at all. I think that they'd even started filming the last three episodes when it turned out that Aidan [Turner] had got his role in The Hobbit. It was ultimately Aidan's decision that he wanted to move on. To a certain extent, I'd been writing his exit for a year or so. After the Box Tunnel Twenty massacre, I always knew that that was ultimately going to be how the character left the series. But whether that happened at the end of series three or the end of series thirty-three, I hadn't made a decision. But ultimately it was Aidan's decision, he felt that it was time to move on. But it happened quite late in the day. I had a slightly different ending planned [for the third series] for if that hadn't happened. Nonetheless, every time we sit down to start storylining a new series, we never know which members of the cast we're going to have, so we have to leave it fairly open-ended. Not just for him, but for all the characters."
"No, if Aidan had decided that he wanted to do a fourth series, he would have had him back like a shot. But we knew from the moment that we first met Aidan, when he came in for his first audition for Mitchell, we knew that this was a guy who was going to become a huge film star. So to have had him in our cast for three years was more than we had any right to expect. It was with no ill feeling at all that we said goodbye to him."
Are there any plans to replace Mitchell with a new regular in series four?
"We would never try to replace Mitchell directly, because I think that he's irreplaceable. I think that the format of the show, which is a werewolf, a vampire and a ghost living in a house, will have to reestablish itself relatively soon in series four. But what the actual specific ingredients of that new format will be, I couldn't possibly comment on!"
Is there any chance that Adam (Craig Roberts) could return to the show?
"I'd love to bring Adam back. If we can find a story for him, then we absolutely will, because I think Craig's performance in Being Human and [online spinoff] Becoming Human was absolutely superb. But we often get requests from the fans to bring lots of different characters back. A lot of people want us to bring Ivan (Paul Rhys) back, for example. The thing is, there's no specific policy not to [bring them back] but ultimately the bottom line for all of our decisions has to be 'What's the best story?'. If we came up with a fantastic story that involved bringing back Adam or Ivan or Daisy, then we'd find a way of doing it. But on this show, we are always slaves to the story, as opposed to who our favourite characters might be."
So presumably the same applies to the werewolf Tom (Michael Socha)?
"Yeah. I don't think I'm giving too much away by saying that we'll be seeing more of him in series four."
"No, I think that unfortunately Herrick was in a way a casualty of Peter Jackson! I'm not sure what we would have done with Herrick if we didn't have Mitchell. But also, I've always felt that with villains, it's good to pay them off and then bring in new villains. For example, in season one of Heroes, they spent the entire season defeating Sylar, and then he comes back! You think, 'What was the point of that'? A lot of fans were very upset when I killed Herrick the first time at the end of series one. They were saying 'That's a ridiculous thing to do' but then they liked the new villains. We'll find new villains [in the next series]. I think that the threat has to keep renewing itself. If the characters are locked in an eternal struggle with the same villain, then it becomes a bit boring. I think it's good to throw up new threats and present them with new obstacles."
Do you think Being Human could move from BBC Three to BBC One or Two, as Torchwood did previously?
"I know that the cast and certain elements of the production would be very pleased if we moved onto another channel, but personally I'm really happy with it on BBC Three. I think it's a really good fit there. The channel's been fantastic to us and we've hopefully been good for the channel, so I'm very happy there. If we stayed there for the rest of the show's lifespan, I'd be very happy. We've got a very good working relationship with them. They trust us to produce the best show that we possibly can, and so I'd be very reluctant to change that. Success is such a weird, elusive, delicate thing and you never know what it is that makes something successful. It's never one thing, it's always a combination of things. It's like when people say 'The show won't be the same now that Mitchell's gone'. No, it's not going to be the same show. But the thing is, while Aidan was an extraordinary, incredible performer, it wasn't just him that made it. As I'm sure he'd be the first to say, it wasn't just about Mitchell. The show is the sum of its parts, and so consequently I'd be loathe to change the chemistry of the show too much by moving onto another channel."
With Aidan gone, the show's regular cast is now predominately female. Do you think the show will become more female-oriented?
"I'd never really thought about it in terms of that. In terms of what the new make-up of the house is going to be in series four, there are more surprises! We've storylined the series, we've started the first five scripts, so there are a lot more surprises and shocks to come!"
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