Billie Piper almost spoiled her surprise Doctor Who appearance weeks before making her return to the show via a dramatic regeneration.
Released on 31 May and titled 'The Reality War', the episode saw Ncuti Gatwa bow out as the Fifteenth Doctor before a regeneration scene revealed Piper, who previously played the Doctor's companion Rose Tyler.
Appearing in Saturday's special episode of Doctor Who: Unleashed, which marked the 20th anniversary of Doctor Who's 2005 revival, Piper nearly gave the secret away.
In a pre-recorded interview, which was posted to the official Doctor Who Instagram page, Piper was asked if she would ever return to the show.
"Yeah I would," Piper said. "I would come back. What's funny is that I never feel like I've left Doctor Who, because there is this huge Doctor Who afterlife."
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"Obviously, people still really want to talk about it, it's a massive fandom, so we do conventions and we meet lots of the fans, and there's always features," she continued.
"It's always on the TV on some channel and a new generation pick it up, so it never feels like it's over, like it does with all the other jobs I've done."
The apparent slip-up happened when Piper said: "So coming back is really good fun." Clearly realising her mistake, she added: "So I would do it, but I still feel like I'm in it. Just a lot older."
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Fans took to the comment section to share their thoughts on the blunder, with one fan commenting: "Accidentally telling on herself there."
"Not Billie slipping up there before it was confirmed," penned an amused fan, while another commented: "You can see she's trying to hide something. Welcome back, Billie. Or should I say 'Doctor'?’"
Speaking recently about her shocking return to the BBC sci-fi franchise, Piper said: "It's no secret how much I love this show, and I have always said I would love to return to the Whoniverse as I have some of my best memories there."
Doctor Who airs on BBC One in the UK and Disney+ elsewhere. Classic episodes of Doctor Who are available on BBC iPlayer in the UK.
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Harriet is a freelance news writer specialising in TV and movies at Digital Spy.
A horror enthusiast, she joined Digital Spy after working on her own horror website, reviewing films and focusing largely on feminism in the genre.
In her spare time, Harriet paints and produces mixed-media art. She graduated from the University of Kingston with a BA in fine art, where she specialised in painting. She also has an MA in journalism from Birkbeck University.
