It’s fair to say that the fifth episode of Doctor Who series 12 ended with quite a bang, revealing an all-new incarnation of the Doctor (played by Jo Martin) whose mystery past shook Jodie Whittaker’s Time Lord to her core.

Another Doctor? Halfway through the series? With no warning? Suffice to say, fans were blown away – and the team behind the series were feeling pretty good about their secret-keeping.

“I think particularly because we had the Master at the start, people thought all our twists were done,” showrunner Chris Chibnall exclusively told Radio Times. “And you never do an episode five twist... I don't know where we'll do it again next time!

“And it's all credit to Jo Martin – just an extraordinary performance.”

In the episode (titled Fugitive of the Judoon) the Doctor and her friends are pulled into a Judoon raid of Gloucester, where the rhino-like aliens are hunting an unknown intergalactic criminal who appears to be either tour guide Ruth Clayton (Martin) or her shifty husband Lee (Neil Stuke).

However, it’s revealed that the Judoon are actually working for the Time Lords and hunting down the Doctor, who had repressed her Time Lord nature with a chameleon arch to hide out as “Ruth” – until the Thirteenth Doctor’s arrival gradually brought her back to herself for the final scenes of the episode.

Given the momentous nature of the twist, fans would be forgiven for thinking Martin’s ‘Fugitive Doctor’ had been part of Chibnall’s gameplan from the start, but apparently the opposite was true. Instead, Chibnall and episode co-writer Vinay Patel only adding her to the action when work on the script was already underway, adding a new dimension to an alien-on-the-run outline.

“We had a story, and Vinay and I were talking about a story... and then I just called him up one day and said 'you know this story...what if that's the Doctor?'” Chibnall recalled.

Jo Martin and Jodie Whittaker in Doctor Who (BBC)

“And he sort of sat and looked at me like 'what?' – so he was the first person to know. And the moment we started talking about it, and we worked really closely together on it in a really great way, it was irresistible.

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“It was something that came about in conversations,” he added. “I was thinking more towards the finale, and then it became... well, there are some thoughts that once you have them, they become irresistible.”

Obviously, such a twist would only work if it could be kept secret, a challenge made easier by Chibnall’s decision to include a familiar Doctor Who opponent to mask the true excitement of the episode.

“It was also part of the reason of bringing the Judoon in, is they were a great sort of wonderful misdirect,” Chibnall admitted. “OK, the thing you're going to be obsessed with in that episode and everybody's talking about because we're doing location shoots is the Judoon.

“Whereas actually, it's the second half that's going to make people lose their minds.”

By the episode’s end Martin’s Doctor had vworped away in her stylish TARDIS, not appearing again in the series beyond a mental projection in season finale The Timeless Children – but already fans were clamouring for more, and the desire to see her again in the series has only been growing since her debut.

So, the pivotal question… which may be what you’ve read through most of this article to find… will Jo Martin be back in Doctor Who, possibly in the now-filming season 13?

The Fugitive Doctor (Jo Martin) in Doctor Who
The Fugitive Doctor (Jo Martin) in Doctor Who BBC

Disappointingly, Chibnall says he hasn’t decided – though he said he had been moved by how well Martin had been accepted by the fans.

“I don't know, is the honest answer,” Chibnall told us. “It hasn't happened yet.

“But the way she's been accepted and the way she's handled it is just beyond our wildest dreams. She's such an exceptional person and actress. Just wonderful, from the moment she came in, the first readthrough...I can't say enough brilliant things about Jo.”

With that in mind, and given Martin’s own enthusiasm for the role (which she called “groundbreaking” in a recent interview), we’d say it still seems likely that we haven’t seen the last of the Fugitive Doctor. Somehow, it feels like all of time and space won't be enough to contain her.

Revolution of the Daleks
The November 2020 Doctor Who preview issue of Radio Times

For more from Chris Chibnall including new design details of the Daleks and his plans for season 13, check out the Radio Times Doctor Who Christmas special preview issue – on sale now!

Doctor Who: Revolution of the Daleks comes on BBC One on New Year’s Day. Want something else to watch? Check out our full TV Guide.