Former Doctor Who showrunner Chris Chibnall reacts to Billie Piper regeneration twist

Last year, Doctor Who fans were stunned by a huge twist in the latest season finale, as Ncuti Gatwa was seen regenerating into Billie Piper, who previously played the Ninth and Tenth Doctor's companion, Rose Tyler.

The mystery of just what's going on, and whether Piper is actually playing the next Doctor, has kept fans guessing ever since, with major figures from the show's past and present including Peter Davison, Colin Baker and Steven Moffat, giving their thoughts.

Now, Chris Chibnall, who wrote episodes for the Tenth Doctor and the Eleventh Doctor before becoming the showrunner for Jodie Whittaker's era as the Thirteenth Doctor, has given his reaction.

Chibnall was speaking with us exclusively for our video interview series The Radio Times Writers' Room, in which we get to know what makes screenwriters tick, when he was asked whether he has any idea where the twist involving Piper is going.

Speaking about the episode in question, The Reality War, which also saw Whittaker reprise her role in a cameo appearance, Chibnall said: "No! I didn't have any clue when I was watching it. The only thing I knew was that Jodie was in that episode. Because also, when I finished, I was very, very clear to Russell that I didn't want to know anything.

"So I really, actually didn't want to know that Jodie was going to regenerate into David. But they were like, 'You have to know this because you're an exec on this episode.'"

He continued: "No, I didn't know, and I love not knowing. I love being back as a viewer again, that's really cool. And, no, I never ask and I never want to know. I want to watch it, because that's the thing.

"That's what takes you back to where you start as a five year old, or whatever, you're there watching Doctor Who and to be back in that position, having had your own TARDIS, in inverted commas - I didn't have a real TARDIS - but it's lovely to then go back and go, 'Oh, what's happening now?'"

In his conversation for The Radio Times Writers' Room, Chibnall also spoke about his work on Doctor Who spin-off Torchwood, Law & Order: UK, Broadchurch and new Netflix series Agatha Christie's Seven Dials.

Seven Dials, an adaptation of Christie's The Seven Dials Mystery, stars Mia McKenna-Bruce, Helena Bonham Carter and Martin Freeman, and follows unlikely sleuth Lady Eileen 'Bundle' Brent as she attempts to unravel a dangerous web of secrets.

Chris Chibnall's interview for The Radio Times Writers' Room will be available to watch in full on Thursday 15th January.

Doctor Who is available to watch on BBC iPlayer. Agatha Christie’s Seven Dials will launch on Netflix on 15th January 2026. Sign up for Netflix from £5.99 a month. Netflix is also available on Sky Glass and Virgin Media Stream.

Add Doctor Who and Agatha Christie's Seven Dials to your watchlist on the Radio Times: What to Watch app – download now for daily TV recommendations, features and more.

Check out more of our Sci-fi coverage or visit our TV Guide and Streaming Guide to find out what's on. For more TV recommendations and reviews, listen to The Radio Times Podcast.