This year’s Doctor Who Christmas special will be going be the name of Twice Upon A Time, it was revealed yesterday. But in a San Diego Comic-Con panel discussing the upcoming episode, Pearl Mackie – who plays Bill in the show – also revealed that it’s likely to be her last episode.

She revealed that she’s leaving Doctor Who following the Christmas special, which means that Jodie Whittaker will require a new companion when she takes the TARDIS keys. Just as when Steven Moffat took over Doctor Who with series five, Chris Chibnall will now have to introduce a new Doctor and a new companion in his first full episode.

Mackie didn’t rule out a return at some point in the future, and said that “it’s been such an amazing journey”. A short one, too, with just one series under her belt. But a series where she made one hell of an impact.