As Doctor Who fans and media pundits currently speculate furiously over who will succeed Peter Capaldi as the Doctor, head writer Steven Moffat probably thinks we’re all getting a little overexcited.

You see, the sci-fi series’ showrunner (who will depart alongside star Capaldi after this year’s Christmas special) has revealed that he considers the recasting of the Time Lord to be less of a shake-up than bringing in a new companion, a process he’s been rediscovering with the debut of Pearl Mackie’s Bill Potts this year.

“You know [when] we change Doctors, you just change Doctors,” Moffat exclusively told at the BFI & Radio Times Television Festival. “It’s the same person, just someone else is playing them. 

“You bring in a new co-lead, and we say companion, but co-lead is a better expression. They have as many lines, they have as much screentime, they are as important to the story.

“It’s a co-lead. The person who asks, ‘Doctor Who?’ It starts you again. And her journey of meeting then realising there’s more to this guy, there’s a Tardis and a time machine, slowly realising he’s this swaggering, immense hero – all those beats are quite fun to play.”

Speaking to us at the BFI Southbank (above), Moffat went on to discuss the interplay between new companion Bill and the Doctor, which audiences will see for the first time this Saturday evening.

“The way he plays off Pearl is different,” Moffat told us. “Because there was a sort of commonality between him and [former companion] Clara that meant he could behave quite… not brutally, but sometimes without due care, and the compassion would come out more occasionally.

“He doesn’t quite know what to make of Bill at the beginning, so he’s more careful. And he’s very much more the grandfather, the tutor, the instructor. Who as it turns out, and she quickly learns, is completely barking mad.

“I think [audiences are] gonna love her,” he added. “I hope they’re gonna love her – we love her. The early indicators in terms of people looking at the show have been very, very good indeed. 

“It’s a wonderful, spirited, engaging performance. And she is quite a different tone of voice for us. I think genuinely quite a different tone of voice for us. But you know, hey… I’ve given up trying to predict.”

Based on what we’ve seen, we’d say audiences are in for a treat with Bill – even if we are still pretty excited about the next Doctor as well. We contain multitudes. 

Doctor Who returns to BBC1 on Saturday 15th April at 7:20pm