Ncuti Gatwa's shock regeneration is followed by an even bigger surprise as the show welcomes back a popular star of TARDIS past. BEWARE! Spoilers ahead!

Speaking of Ncuti’s departure, Russell T Davies, Showrunner said: "What a Doctor! Thank you, Ncuti! As his final words say, this has been an absolute joy, and the team in Cardiff and everyone who has worked on this show for the past few years, are so lucky to have been part of Ncuti’s great adventure as he shoots off to stratospheric new heights."