Steven Moffat has said fans will have to wait and see whether the show will buck the trend in future and have a companion who isn’t another modern day Earth female.

Speaking at the recent Royal Television Society panel: “As to changing it up with the companion, we actually have changed it up quite a lot, look how different those girls have been. Wait and see.”

He adds: “What we have is probably the most enduring form of the show and I think will always tend back to it for whatever reason, but there’s no reason you couldn’t tend away from it and there’s no diktat or special rule book left by Verity Lambert or something.

“We absolutely could vary it. The times they’ve varied it, it makes them work hard – you can see them struggling with Leela. She was a great character but they had to civilise her fast because it was getting hard to fit her into stories – but it’s not a hard and fast rule at all.”