Doctor Who: Flux star reveals their character was supposed to die early in the series

“Originally, there was no guarantee that the Sontarans were coming back,” Watson told RadioTimes.com.

“I think in the first script, I was kicked over a cliff, dead. Thankfully, that was rewritten. The script [for episode two] is now along the lines of me saying to Jodie [Whittaker], ‘I will return.’ So I knew, then, it was going to be OK.

“No, it was good to come back for the finale, and it was great to go back down in the spring of this year, to complete it. I really enjoyed it.”

In Survivors of the Flux, it was revealed that the Grand Serpent (Craig Parkinson) had been working with the Sontarans all along, using time travel to weaken Earth’s defences against extra-terrestrial attack – and apparently this partnership will continue in the finale as the invasion begins.

“When you go into a long-running series, especially something as iconic as Doctor Who, you’ve got to hit the ground running,” Watson told us.

“To do that, you’ve got to feel part of it all, and that’s what everybody was great at, especially Jodie. She made me feel so welcome, right from the off.

“So it was very easy to get into the rhythm of things. I absolutely loved working with her, and John Bishop. And then when I come back, you’ll see that most of the stuff is with Craig Parkinson. It was a great job to do.”

Exactly what the Sontarans get up to in the finale remains unknown – Watson promised “confrontation and destruction” with no further details – but for now, we’re just happy they didn’t all fall off a cliff in episode two.

“The fans’ reaction has been so positive, saying it’s got back to what they were – a warrior race – and less of a comedic sort of approach that’s still quite funny, but the main thing is that they’re warmongers. And that’s what you’ve got to try and get across,” Watson said.

“People responded very positively about the sort of route I took. So I was pleased at that. Relieved and pleased!”

Read more about Doctor Who:

• Doctor Who: Survivors of the Flux podcast review
• Doctor Who: Survivors of the Flux’s 9 biggest questions
• Doctor Who’s Brigadier cameo makes an even bigger mess of UNIT dating
• Can Doctor Who: Flux stick the landing?

Doctor Who: Flux’s final episode airs on BBC One on Sunday 5th December. For more, check out our dedicated Sci-Fi page or our full TV Guide.