Catherine Cawood (Sarah Lancashire) was trapped in a cat-and-mouse chase with Tommy Lee Royce (James Norton) for the third and final series of Happy Valley.
The BBC drama concluded with Catherine confronting the rapist and murderer in a satisfying ending as Tommy set fire to himself while the lovable police woman walked away.
Happy Valley creator Sally Wainwright addressed the future for Catherine as she spoke out on her own fears over whether the finale would do the series justice.
Speaking on Newsnight, Sally said: "I tend not to very get nervous anymore really, I'm kinda philosophical that it is what it is and people will respond how they respond."
"But I think because it appeared to be doing very well I was worried it might fall at the final hurdle and people might think it was a disappointing ending in some way but I kinda knew it wasn't. I knew it was what I wanted it to be," she continued.
"It was satisfying. I had a real choice about whether to end on a pessimistic note or an optimistic one.
"Which one of them was gonna survive but it was a no brainer to end on an optimistic note with someone like Catherine. She's such a force for good."
Sally revealed the ending could have been very different without the input of Catherine star Sarah.
"I have Sarah to thank for that ending in many ways," the writer continued. "I wrote the first draft and everyone seemed happy with it and she made it clear she wasn't happy with it.
"I think last Christmas, the Christmas before, [Sarah] came to my house and gave me some really good notes and pushed it a bit further and I have Sarah to thank for that."
Sally said: "It was a great privilege to have the opinion of someone who knew the scripts almost better than I do... she was literally here all day at my house talking it through. Her performance is just off the scales."
Happy Valley fans will be disappointed to hear there's no chance of Catherine making a reappearance.
She told Newsnight the third and final series is "definitely it" and expressed the importance of "knowing when to stop".
However, Sally did hint at Catherine coming out of retirement one day: "Maybe she will. But we won't get to see it."
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