The writer teased the death during a BBC One Facebook Live event following tonight's episode of the show after he was asked about the character's fate, saying: "Yes, that's it. She's a Cyberman from now on. She was killing people from the trailer. That's the way it is sometimes."

Actress Pearl Mackie, who was also taking part, said: "I mean, I'm quite an emotional person, so it was pretty emotional even just reading any of it and at the read through it was quite emotional because there's a lot of endings.

"I think that's the credit to Steven's writing that you can get that kind of emotion from it when you read it that you're supposed to get when you watch it."

The companion's fate has not yet been confirmed either way but it's not looking good for the canteen worker either way.

Bill Potts was killed off this evening after she was shot through the chest and turned into a Cyberman after getting captured by some sinister creatures.

The instalment ended with a Cyberman from Mondas angrily walking towards the Doctor (Peter Capaldi) as it was revealed that Bill was inside the suit of the homicidal robot.