Watch: BBC reveal finale trailer but is there any happiness in Happy Valley?

In a recent episode of writer Sally Wainwright’s acclaimed crime drama, it was revealed that the collection for a retirement present for Sgt Catherine Cawood, the dedicated police officer played by Sarah Lancashire, currently stood at over £2,000.

Apparently even people she’d previously arrested had been dropping into the station to contribute to the whip round.

Quite a few viewers probably wondered if there was any way they could chip in as well. There’s nothing many of them would like more than for the third and final series of Happy Valley to end with Catherine fulfilling her retirement dream of driving to the Himalayas, preferably with a substantial wad of cash in her pocket and the well-wishes of the local cops and criminals ringing in her ears.

But why have audiences taken Catherine to their hearts? Writer Wainwright believes it’s all down to Lancashire’s performance saying: “I think that she is an extraordinarily empathetic performer. I think she conveys the real subtleties of the tiny, tiny moment-by-moment thoughts in everything she does. The audience really engage with her.”

While Lancashire has been extraordinary, there’s no doubt that Catherine is also a gift of a role. Wainwright describes the character as “very strong and very stubborn".

“I think she has got a very strong streak of irony and comedy. What I often think about Catherine is that she is a good person to whom something very tragic has happened. That informs the character that she is now. That she has got this streak of tragedy that strikes through her, but she is somebody who prior to that was very amusing and entertaining and good fun. She is strong, I think police officers have to be strong.”

As we reach the final episode though, what viewers really want to know is whether Catherine is in for more tragedy. It’s been claimed that even the cast don’t know what will happen as multiple endings have been filmed.

What we do know is that is that it’s Catherine’s final shift and some old scores are about to settled, while her grandson Ryan (Rhys Connah) is faced with a moral dilemma.

We can also safely assume that it’s going to be tense – episode two had viewers on the edge of their seats just by showing Catherine sitting outside a café in Sheffield, looking through the window as her sister Clare (Siobhan Finneran) lied to her on the phone about being in Leeds.

The following episode raised the stakes even further as dodgy pharmacist Faisal (Amit Shah) progressed from handing out prescription pills to committing murder, and Catherine’s arch-nemesis Tommy Lee Royce (James Norton) staged a daring escape from court.

Whatever happens though, it seems this really will be the final series.

Looking to the future, Wainwright says: “The intention developed through conversations I had with Sarah to make it a three-parter, to make a trilogy. We always said this would be the final season and it very definitely is the final season.”