Peter Capaldi, Steven Moffat and Michelle Gomez discuss leaving Doctor Who

What’s it like reaching your final series as showrunner?

Well, we’ll show up again at Christmas – apart from Michelle. I seem to have been reminiscing my way out of the door for about two years. It’s the longest departure in human history. I never intended to do it for ever and the workload is staggering.

I’m just at the end of my toughest ever year in which I’ll have done – in about a year – three Sherlocks and 14 Doctor Whos. That’s been shattering. Doctor Who has to move on and be different and shed me like a scale of a mighty dragon as it shambles off to another battle.

What’s the scariest monster you’ve created?

I think the Weeping Angels. We used to stay in a hotel in Dorset and next to it was a marvellous church with a chained-up graveyard and the words “unsafe structure” on the gates. I looked into the graveyard and could see a stone angel with its face in its hands as if lamenting.

I put the chained-up gates into the very first shot of Blink [a 2007 episode] and then I made up the Weeping Angel and I was very proud and excited. A few years later I said to my son Joshua, “Come and have a look at this. I’ll show you the original Weeping Angel.”

We went back to the graveyard and the angel wasn’t there – it was gone. So either I misremembered or they’ve moved it or there’s a real Weeping Angel in the world moving around when you’re not looking.

What’s the hardest thing about writing Doctor Who?

There are degrees of difficulty rather than degrees of ease. The Day of the Doctor [the 50th anniversary special in 2013] with all the pressure on the storyline and all the stars appearing in it was just a nightmare. I was never so happy with anything as when that became such an immense hit.

How would you describe your Doctors?

He is someone who’s running towards everything at once because he might miss it. He doesn’t understand why anyone would do the same thing every day or sit in the same room every day. He doesn’t understand why you would live a life in safety when you could be running from fires and explosions. He doesn’t understand why we volunteer to be dull – he needs to be out there and experiencing everything at once.

Along the way, of course, he helps people and people start to think of him as this great hero, but he doesn’t understand that – he’s just running past people and seeing that they need help, so he helps. Actors either have it or they don’t. The first time I saw Matt Smith – only the second person to audition for the role – you could instantly tell that he was Doctor Who. There was nothing clever about saying, “Well, obviously it’s him.”

How do you bow out?

I’ll strike a balance between not revealing spoilers and trying to get people to watch. I’m honour-bound as a writer not to give a damn about my departure. There’s no story about me leaving, the kids don’t know I exist – you can’t really get me away from the balcony when nobody knew I was in the building.

But it’s about giving Peter a grand, several-stage finale and trying to refresh the story that Doctor Who gets involved in with a tremendous crisis, during which he gets in some way mortally injured and has to turn into another actor.

Who would you cast as the next Doctor?

I think it should be me. That would be awesome. It’s about time they let a writer play the lead. I mean, I’ve been making up everything he says for years, so I can totally do it.

Doctor Who continues on BBC1 this Saturday 24th June at 6:45pm