Exclusive: Mark Gatiss talks Peter Capaldi's Doctor Who exit – and whether 'Empress of Mars' is his own swansong

Mark Gatiss has written for Doctor Who ever since the show returned to our screens in 2005 – that's nine adventures in 12 years. And now, sadly, it might all be over.

Having worked alongside both Russell T Davies and Steven Moffat, the League of Gentlemen star and Sherlock writer has suggested that his time working on the good Doctor might have come to an end, with Torchwood and Broadchurch chief Chris Chibnall ushering in a whole new era as showrunner from 2018.

With what might be his final contribution – an Ice Warriors vs. Victorian-era soldiers romp called 'The Empress of Mars' – airing this Saturday night, Digital Spy grilled Gatiss on reinventing classic monsters, Peter Capaldi's impending exit and what the future holds.

You've already had one crack at the Ice Warriors in 2013 episode 'Cold War'. What did you want to do with them this time?

"Well, I just said to Steven, everything's coming to an end, can I do the story I've always wanted to do, which is the Ice Warriors on Mars? I didn't actually have a story at that point [laughs]. I just always wanted to explore more of their backstory.

"Considering they were always such a big presence in Doctor Who, we know an extraordinarily small amount about them. And I found that doing 'Cold War', that it was rather thrilling to be able to create new things, to give them some backstory and history, just with occasional little windows onto things.

"And I thought, 'Well, we can do Mars, it's practicable.' They're a very cool monster – or a very cold monster – and I just wanted to do something new with them, which was to introduce the Ice Queen into the mythology."

Yes, this is the episode's big twist – how much can you say about this new type of Ice Warrior?

"It's not a twist, really, there's just a female one – and about bloody time, I would say! I thought that it would be an interesting thing to do – rather than just some frozen Ice Warriors, the usual thing, that there was a queen involved, and just give it a different slant, really.

"I have to say, it suddenly occurred me to that the Ice Warriors have such a history of being frozen and woken up after their time, I think they must've got their hibernation equipment from the same people who sold them to the Silurians!

"It's always the same: 'How long have I been asleep?' 'A lot longer than you think!' 'Oh shit, again?' It happens all the time!"

It does seem like such a natural thing to do. Why do you think it has taken so long to set an Ice Warrior story on their home planet of Mars?

"It's taken more than 50 years, because [Ice Warriors creator] Brian Hayles's original second story, what became 'The Seeds of Death', was called 'Lords of the Red Planet' and it was precisely that.

"I'm sure it was to do with budget and scale. I mean, it took till [2009 episode] 'The Waters of Mars' to do an actual Doctor Who story on Mars, which is remarkable really when you think it's essentially a red desert, something that feels very achievable. Except my whole story's set underground, so we didn't even have to go up top.

"It's to do with scale – if you want to do Ice Warrior society, you have to do a fragment of it. We just don't have the budget to do a whole city on the surface, with thousands of Ice Warriors and different levels of society.

"So as is always the way with Doctor Who, and as it should be, it becomes a sort of 'bottle story' of what's happened to this particular group, in this particular part of Mars, without having to do the whole of Mars. Though that would be lovely, wouldn't it?"

Via Digital Spy