Millions of viewers to watch Peter Capaldi become twelfth Doctor

Peter Capaldi is perhaps best known for his role as the foul-mouthed spin doctor Malcolm Tucker in The Thick Of It. Photo: Rankin/BBC

Millions of viewers will tune in to Doctor Who tonight to watch Matt Smith hand over the controls of the Tardis to the latest incarnation of the timelord in Peter Capaldi.

The show's main writer, Steven Moffat, said he is not worried about signing up self-confessed fan of the show Capaldi to the starring role.

"He can absolutely separate the two things. I mean, he can separate the job he's doing from the fact he's a fan of it," he said.

Smith said he has no doubts about Capaldi either, saying: "I don't think anything can prepare you for the experience of what being the Doctor in Doctor Who is but I think he's as ready as he can be.

"I've just said 'Have a good time, mate'. He'll be great. Peter will hit the ground running and keep flying."

Matt Smith was announced as the eleventh Doctor in 2009. Credit: PA

Smith said he is looking forward to bowing out and that Moffat has given him a great exit.

"I'm really excited about Christmas. I think Steven has written a real belter for me to go out on and I had a great time filming it.

"It was quite sad at the end, obviously, when I had to leave, but I think we've got a really moving story, a really great sense of adventure in it which I'm pleased about because it's obviously the last episode but it still feels like a classic adventure episode with great monsters and a few twists."

Former Doctor Who actors (L-R) Tom Baker, Peter Davison, Colin Baker, Sylvester McCoy and Matt Smith. Credit: PA