Sally Wainwright, the show’s writer and director, had previously confirmed that it would be back for a third season, but had not stated when it would return.
Now, the show’s executive producer Nicola Shindler has revealed that new episodes would not appear in 2017 because of Wainwright’s other creative commitments.
In an interview with the Radio Times, Shindler said that Wainwright was working on a new programme for BBC One.
"We are working on a new idea for Sally for BBC One which will be next year so the earliest Happy Valley would be would be towards the end of 2018 I would suspect.”
"She won't write the [Happy Valley] scripts for some time but Sally's determined to do it."
Happy Valley revolves around police sergeant Catherine Cawood as she tackles a dark figure from her past in the Yorkshire town of Calder Valley.
The show has been critically acclaimed and enjoyed its second series in February of this year.
As well as other commitments, Nicola Shindler claimed that the idea for the plot of series 3 requires one of the characters to be older in order to make sense.
“If you look at the characters that are left, there is Sarah, there is James Norton and there is a young boy, who the minute he turns into a teenager it becomes a much more interesting story."
“She doesn't know what the story is yet. She is mulling it in her head but we are thinking about giving it a bit of space in story term."
Series one of Happy Valley is available to stream now on Netflix.
Source: Digital Spy