Reports in the tabloid press have claimed that Millie is set to be replaced in the BBC series by Varada Sethu.
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Heartstopper star Yasmin Finney made her debut as Rose Noble in Doctor Who last year.
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Millie plays the Fifteenth Doctor's new companion Ruby Sunday – but soap fans may well already recognise her.
"It was so not what I was expecting."
Here's why the actor never appeared on the show.