Set in West Yorkshire, it became a massive hit when it first hit screens almost two years ago and it’s back for a new series this week.
Sarah Lancashire, who plays old-school Sergeant Catherine Cawood, says beat bobbies, as well as viewers, were impressed.
“The feedback we had was that they had never seen a police officer portrayed as accurately,” said Sarah.
“This is down to our police advisor.
“She is retired from the force now but she was a sergeant and whenever we do any sort of procedural stuff she is with me.
“She takes no nonsense and gets on with the job.”
Viewers were shocked when Catherine took a vicious beating in the original run but Sarah says she felt the way it was done was absolutely right.
“Catherine is a police officer and the violence she was subjected to in series one is what female police officers can be subjected to every day of the week.
“I would never condone anything which I thought was salacious, titillating or gratuitous.
“If you replayed the violence from series one, what you think you saw you probably only heard because it was shot beautifully.
“It was an absolutely honest portrayal of what a female police officer can be subjected to.”
This series follows the hunt for what appears to be a serial killer after a spate of murders.
Original killer, Tommy Lee Royce, is behind bars in this one but still a key character.
“He is still a psychopath, it’s not like he has reformed,” says War and Peace and Grantchester star James Norton.
“His son Ryan provides glimmers of hope, but they are gone as soon as they arrive and he goes back to this dark, hostile, nasty place.”
Happy Valley, BBC1, Tuesday, 9pm.