'Doctor Who' Season 9 Spoilers, Cast News: Jenna Coleman Will Not Be Leaving Series

Actress Jenna Coleman was planning to quit BBC's smash science-fiction series "Doctor Who" last year but suddenly changed her mind and stayed on, the show's chief writer Steven Moffat disclosed.

Coleman, who started her career in the ITV soap "Emmerdale" as Jasmine Thomas, is set to come back as the Doctor's companion when "Doctor Who" returns to the BBC this autumn.

Her move makes her the longest-serving assistant of the show's modern era, ahead of Karen Gillan and Billie Piper, BBC wrote.

Coleman was widely reported to be ready to leave her role as Clara Oswald after a cliffhanger in the finale "Death In Heaven" of the show's series eight.

Moffat told Doctor Who Magazine that Coleman had asked to be written out of the series.

"That was her last episode," Moffat was quoted as saying by BBC News. "Then she asked me if she could be in [the] Christmas [episode]. So I said, 'OK, I'll write you out in Christmas.'"

"She came to the read through and did the 'Write out' version – and again changed her mind."

"But the truth is, I never wanted her to go. And with last Christmas, I'd already written the alternative version where she stayed, and I preferred that version," Moffat said. "Frankly, I didn't want to lose her. She's an amazing actress, and she never stops working to make Clara better. I was very happy to go the extra mile to make sure we could keep her."

The 28-year-old actress from Blackpool confirmed her return to the show last December, saying: "I couldn't walk away with the story being unresolved."

"The arrival of the 12th Doctor has just kind of dropped this whole bombshell and allowed the dynamic to totally change, so I think just when Clara was feeling more comfortable in the relationship, it has suddenly thrown something new up," Coleman said.

Peter Capaldi, who plays the titular lead character, said: "I'm thrilled. Jenna has just been fantastic and such a pleasure to work with."