It's a Sin star Nathaniel Curtis makes surprise Doctor Who appearance

The episode's pre-titles sequence saw the Doctor and Donna land the TARDIS on top of the very same tree that dropped an apple on Isaac Newton's head, leading him to discover gravity... or should that be "mavity"?

Newton was played by It's a Sin star Curtis, whose casting was not announced prior to the episode being broadcast.

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Speaking at a Q&A following a screening of The Star Beast, Davies previously said of the secretive episode: "It's weird, the next one, it's kind of scary. It's not super scary, it's just weird."

The story of the Fourteenth Doctor will resolve in The Giggle, the third and final Doctor Who anniversary special, which will also introduce Ncuti Gatwa as the Fifteenth Doctor.

Gatwa's first official episode will then follow just 16 days later, airing on Christmas Day on BBC One.

Titled The Church on Ruby Road, this instalment will also see Millie Gibson make her debut as new companion Ruby Sunday.

Doctor Who's third anniversary special The Giggle airs at 6:30pm on Saturday 9th December on BBC One and BBC iPlayer. Classic episodes are available on BritBox – you can sign up for a 7-day free trial here.

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