Some writers’ creative juices start flowing once they bounce ideas about with a pal.

Others might come up the magic staring out of the window of a bus.

Now Doctor Who showrunner Russell T Davies has revealed the secret to his success may be down to a staple part of his morning routine.

“Honestly I swear to you, brushing your teeth,” the 61-year-old said.

“I think everything is kind of worked into my mind overnight.

“And you wake up, and you brush your teeth and things click into place.”

He compared coming up with ideas in this way to the game Wordle.

“You know, leave it for an hour, and suddenly the word is there,” Davies told Radio Wales’ Behnaz Akhgar.

“I think a lot if life is [like] that. Your subconscious goes ‘click, click, click’ and ticks through all the algorithms and ideas.

“So brushing your teeth, honestly, sometimes things go ‘boom, boom, boom’.

“I’ve thought of entire shows brushing my teeth.”

When it comes to putting pen to paper, Davies locks himself away.

“I’m very suspicious of those people who sit in cafes,” he said.

Though it has been almost 20 years since Doctor Who returned to TV screens in 2005, Davies still gets nervous before broadcasts.

The latest Christmas instalment of the series is being shown on BBC One on Christmas Day.

The episode, named Joy to the World, is about a hotel with a different world in every room.

“You do feel the pressure and you should, that’s part of the job,” he said.

“You get the fear, you don’t want to disappoint.

“You’ve got to say something new, you’ve got to have impact, so that is a great fuel to the engine all that stuff.”

The Doctor’s companion on the Christmas show will be Derry Girls and Bridgerton star Nicola Coughlan.

“She knows Ncuti Gatwa, the Doctor, and they were both in the Barbie film,” Davies said.

“On social media, they kind of like chat, and they know each other in that mad social world that actors live in.

“So it was an offer she very quickly accepted. We’re delighted.”

Davies is also working on a Doctor Who spin-off called The War Between The Land And The Sea.

He said: “It is a different show, it does not have The Doctor in it. We have done that over the years. There was Torchwood, which was set in Cardiff and the Sarah Jane Adventures.”

The new series stars Russell Tovey and Gugu Mbatha-Raw.

In it an ancient species emerges from the ocean, triggering an international crisis.

Davies said: “When you look and see what we have done to our seas, if you lived in the ocean, if there was such a thing as an ocean creature, wouldn’t you be furious?

“Haven’t we ruined them?”

The Doctor Who Christmas special is on iPlayer and BBC One from 17:10 GMT on Christmas Day