It was always fair to assume that the 2017 Doctor Who Christmas special wouldn’t be the most merry of festive episodes, with the upcoming Twice Upon a Time set to feature the “death” of Peter Capaldi’s Twelfth Doctor (before regenerating into Jodie Whittaker’s new incarnation) and the end of a seven-year era in Doctor Who history.

However, it’s now emerged that the episode could be even darker than we expected, with the episode’s writer Steven Moffat (who departs as showrunner alongside Capaldi this December) hinting that there could be some nasty times ahead for the Time Lord.

Speaking at a panel at the London Screenwriters’ Festival, Moffat was asked how he and Sherlock co-creator Mark Gatiss (also present with producer Sue Vertue) balanced the Baker Street sleuth’s selfish tendencies with his essentially good nature – and his answer included a fascinating Doctor Who tidbit for attentive fans.

“Why would Superman be good? Because kindness stops you being lonely, would be the answer,” Moffat said. “That’s what that’s about, for Sherlock Holmes.

“He’s good because for all he protests about it, there are people he cares about.

“So, kindness is what makes a unit of us. So if you are sane and rational, kindness is by far the best path. There isn’t anything rational about being vile and awful and evil. It’s not actually a good strategy.”

He then added cryptically: “Prepare for that to be contradicted on Doctor Who on Christmas Day…”

Now, we’re not sure whether the “vile and awful and evil” comment refers to some dark, utilitarian idea enacted by the Doctor in the episode, the successful evil plans of his enemies or even his own ruthless nature when it comes to telling the story of such a crucial episode.

But whatever the truth, it sounds like the Twelfth Doctor’s final stand is definitely going to be one of the darker offerings on TV this festive period. Yes, even more so than The Snowman.

Doctor Who returns to BBC1 this Christmas, and the London Screenwriters’ Festival continues all week