'Happy Valley' will come to an endbefore 'the rot sets in'.

Sarah Lancashire as Sergeant Catherine Cawood

Sarah Lancashire as Sergeant Catherine Cawood

The mastermind behind the police drama, Sally Wainwright, has admitted she never writes for one series, but instead for a sequel, but she won't allow the programme to drag on too long because she fears the storyline will start to "rot."

Speaking to The Daily Star newspaper about the hit show, the Bafta-winning writer said: "I never plan to write one series of anything. You only write one series if it's not successful, and you don't get recommissioned. But it's when shows get into fifth, sixth, seventh, series that the rot tends to set in."

The intense six-part drama - which has followed matriarch Sergeant Catherine Cawood (played by Sarah Lancashire) investigate numerous killings of prostitutes in West Yorkshire, whilst trying to uncover the mysterious person behind grandson Ryan's (Rhys Conna) birthday present - came to a dramatic end last night (15.03.16).

The explosive finale saw Detective Sergeant John Wadsworth (Kevin Doyle) plummet to his death after being unveiled as the culprit behind his mistress Vicky Fleming's (Amelia Bullmore) brutal murder.

Meanwhile, the popular drama is set to return for a third series next year as more unexpected twists hit the village.