Doctor Who’s companion Jenna-Louise Coleman is set to leave the hit BBC show.
The actress, 28, is believed to be quitting her role as the Time Lord’s assistant in a sensational Christmas storyline.
Her exit could bring an end to her 18 months as Clara Oswald, creating a vacancy for another sidekick to star alongside new Doctor Who, Peter Capaldi.
Yesterday a source said: “The conversations about Jenna’s exit have started, and a plan is in place which is being ironed out.
“By the time she leaves she will be one of the longest-standing companions ever. She has been absolutely brilliant in the role, but everyone agrees it is a part that should change after a period.”
The source added: “It was very much a mutual decision.
“It’s important to keep the series moving and fast-paced, and the time is just starting to feel right and the feeling is that it could be a perfect Christmas storyline.”
The Doctor’s “companion” has become a key part of the success of the iconic sci-fi series, which returns to our screens on Saturday.
There have been almost 60 since the launch in 1963.
Other stars who have occupied the role include Karen Gillan as Amy Pond, Catherine Tate as Donna Noble and Billie Piper as Rose Tyler.
Speculation had been rife among the show’s fans about whether Jenna’s character Clara would have a romantic liaison with new star Capaldi, 56, who takes over from Matt Smith.
However boss Steven Moffatt dismissed the suggestion but hinted that Clara’s relationship with the Doctor is set to change dramatically with Peter Capaldi’s arrival.
He explained last month: “He’s not as immediately approachable and he’s not necessarily looking for your approval.
“I would like to restore the sense that when he says, ‘Wait here, I’ll be back’, you really hope he’ll be back, but you’re not absolutely convinced. What he’s not doing is reassuring you very much.”
And he added that the impact on his companion would be clear, explaining: “From a Doctor she could sort-of control because he had a crush on her, she’s landed with a Doctor who barely registers that she’s a girl.
“They’re great friends and all that but she has to be his human interface with everybody else.”
Adding that the series will become “more serious”, he said: “One of the watchwords we have this year is there are consequences for choosing to live like this.
"It’s not a fairy-tale – we want to make it feel that these adventures can hurt.”
The BBC refused to comment on Jenna-Louise’s exit.