John Barrowman has posted a teasing video on Facebook, revealing that he’s returning to Cardiff later this month.

The Arrow actor had been in Cardiff at a signing session at Waterstones to promote his latest book.

Barrowman hinted in the video: “I will be back in Cardiff in about a week and a half… but I’m not telling you what for!”

Doctor Who is due to begin filming again in Cardiff this month.

New companion actress Pearl Mackie is still performing in The Curious Incident of the Dog in the Night Time at London’s Gielgud Theatre until June.

Peter Capaldi previously revealed: “I don’t know whether [the new companion] would be involved in the Christmas special, because it’s so specific, the story we’re doing with the companion.”

It looks likely that the first episode to be shot once production starts will be this year’s Christmas special (as that’s the next episode to be broadcast), so it seems a safe bet that Mackie’s character Bill will not be introduced until the first opening episode of Season 10 next spring – further backed up by her introduction clip, featuring Bill and the Doctor heading back to “2017”.

Following the return of River Song in last year’s Christmas special, ‘The Husbands of River Song’, could 2016’s festive episode feature a comeback for Captain Jack Harkness?

It would certainly make sense that Steven Moffat would want to revisit the character that he introduced back in 2005’s ‘The Empty Child’ before his time as showrunner comes to an end.

> Here’s everything we know so far about Season 10.

Moffat has said before that as “a massive character in Doctor Who mythology”, the return of Captain Jack “would have to be seismic, not routine” – but that the possibility of him returning is “never, ever closed off.”

John Barrowman last appeared as Captain Jack in Doctor Who in ‘The End of Time: Part 2’ in January 2010.

> Buy the complete Doctor Who Season 9 box set on DVD on Amazon.

> Buy the complete Doctor Who Season 9 box set on Blu-ray on Amazon.

Would you like to see Captain Jack back in Doctor Who this Christmas? Let us know below…