The Moff has been lying for some time.
There was a shortlist of one.
"The list went 'Peter, Capaldi'. It was a very short list. Honestly, there was only one audition list, and it wasn't an audition really, so much as he came round my house and we put him on video to see what he looked like as the Doctor, and gosh, he was terribly good. He's been doing that most nights, I think."
Capaldi really was considered and discarded last time round.
"He did flick through my mind when we were replacing David and he didn't feel right at all. But there's something about Matt's Doctor that paves the way for Peter's Doctor, I think. The important thing to remember about the Doctor is that it's one character going through his life played by a succession of different actors, and you have to get to that place each time. I can absolutely believe that the strange old/young Matt Smith will change into the strange young/old Peter Capaldi."
The Doctor never really changes.
"You'd be surprised how similar the Doctors are on paper. If you look at discarded scenes from previous eras, he's kind of always the same, he's just this very clever man. When he walks around with a different face and voice, it becomes different. When I wrote [Matt's opening episode] The Eleventh Hour and I handed it in, everyone said it was exactly David. Then a few weeks later we cast Matt and everyone was complimenting me hugely – and I accepted the compliments – about how well I'd rewritten it for Matt. I hadn't touched a word, they were just imagining Matt. The Doctor is the Doctor."
Age ain’t nothing but a number.
"The apparent age of the Doctor makes no narrative sense at all. He's been everything from his 20s to his 70s – obviously he doesn't care, he just sort of picks a face off the rack and goes with it.
"I think it's good that we've got a different age just because I can't imagine what somebody in their 20s would do with the Doctor after Matt showed us all how to be a 20s Doctor. I don't know what you would do after that. You'd have to be an alternative or a contradiction. It wouldn't work. So it makes life easier that Peter is different, but that wasn't the reason. It was because the Doctor was in the room."
The future is unwritten.
Secrecy doesn’t really matter after all.
"I thought we should have phoned them and said 'are you home, we'll start the show when you are'. It was fraught, but not because of the secrecy. Does that matter? Not really. It matters that people love the choice. And when we saw that there were some minor degree hints that it was going to be Peter, everyone was rapturous about the idea. If a secret breaks, nothing happens. Somebody just makes a tremendous profit in a betting shop."