When the final series of Happy Valley was announced, Sarah Lancashire said: “It’s time to let the dog see the rabbit.” I think it’s fair to say the rabbits have been well and truly run to ground in a heartstopping conclusion that cleverly made space for a cleansing redemption for its central character. But what is it about Lancashire’s portrayal of Sgt Catherine Cawood that has had more than 11 million of us glued to the screen? The short answer is the happy conjunction of a writer and actor both at the peak of their powers. But that’s only the beginning of the story. Writer Sally Wainwright grew up in the valley she presented to us; she has a visceral understanding of what life is like behind the curtains in the Calder Valley. Behind the fudge shops and tourist information offices, the pilgrimages to Sylvia Plath’s grave and the hillwalking day trips, there’s another world. A world where poverty and joblessness make people easy targets for drug gangs and the fractured relationships that come with those issues. It’s a world where no officialdom is respected. The police in particular are despised and distrusted but nobody gets away scot free. The community centre where Cawood’s sister Clare volunteers is accepted precisely because it’s run by unpaid locals. It’s the kind of backdrop that is often exploited in crime dramas and novels. Lazy writing uses it as a shorthand for lives that are “not like us”, providing a voyeuristic portrait of the underbelly we can watch with relief because those lives don’t touch ours. Happy Valley is a different sort of animal – and its difference lies in that central character. Wainwright understands the humour that makes the hellishness survivable; she sees the courage and compassion that carve out the character of Catherine Cawood and tempers them with anger, fear and frustration to create someone we believe in and root for. Cawood is a distillation of the northern matriarchs we have come to love down the years, from Coronation Street’s Ena Sharples and Elsie Tanner onwards. Their hard-won wisdom is always tempered by mis-steps; they have to haul themselves back from the brink of disaster in ways that often drag more problems in their wake. But always, their dark humour makes us smile and wince and gives them respite from the bleakness of their lives. The men are feckless or violent or insensitive or misogynist. Sometimes all four. They need to be discarded or saved. And we’ve seen women cops before: Juliet Bravo, The Gentle Touch, Prime Suspect, Unforgotten. But none has had the intensity of Cawood, nor have their traumas been allowed the same breathing space as has her battle to negotiate the malign actions of Tommy Lee Royce. His psychopathic magnetism is the constant foil to her passionate need to save her family. So there are plenty of foremothers for Cawood, plenty of tropes for Wainwright to unpick and remake in her own inimitable style. She has been working up to this high point, sharpening her wit and finding tough routes for her characters to follow. At Home with the Braithwaites could have been a cosy comedy drama about the impact of a massive lottery win on an “ordinary” family. Wainwright’s setup of a matriarch who tries to keep the windfall secret provide cues for all sorts of darkness and frailty to surface. Scott and Bailey gave us a pair of female detectives working the unglamorous end of CID and revealed complicated private lives but also showcased a different style of interview technique light years ahead of the “good cop, bad cop” style beloved of cop shows. Last Tango in Halifax revealed the pitfalls and pratfalls of a multi-generational family suddenly dragged into each other’s orbits by the unexpected reunion of two elderly suitors. It could have been saccharine, but in Wainwright’s hands, it had more prickles than a hedgehog. From murder to misunderstandings, it won our hearts and minds and, on occasion, provoked social media outrage. Gentleman Jack broke all sorts of historical taboos and allowed Wainwright to reveal the swashbuckling adventures of Anne Lister, a pioneering 19th-century industrialist and lesbian who shocked society and lived the life she wanted in the face of huge social opposition. What all these shows had in common was their astringent wit that confounded our expectations of what drama should do. Heartbreak and humour are seldom comfortable bedfellows, but Wainwright has created her own grammar of storytelling that is compelling and realistic. Not to mention the magnificently inventive sweariness employed by Cawood. I grew up in Scotland where there is a similar tradition of laughing in the teeth of adversity. The kind of crime fiction I write is salted with humour, mostly one-liners or smart ripostes. For me, compassion and courage in the face of grief are keynotes to my central characters, almost all of them women. I see in Happy Valley the kind of universe I have tried to create. My Karen Pirie and Carol Jordan would recognise a kindred spirit in Catherine Cawood. So I have nothing but respect for what Wainwright has achieved here. But the skill of the trope-busting writing would be wasted without the empathy and the bravery of Lancashire. She inhabits the character of Cawood without a bum note over 18 hours of demanding performance. A tiny movement of her facial muscles is worth a hundred words. Her sardonic take-downs remind me of a tutor I had at university. She would deliver withering one-liners that often didn’t properly land till I was walking away an hour later; we see on the faces of Cawood’s targets that same slow dawning of what has just been said. And for an actor whose career was launched as a blond bombshell on Coronation Street and whose subsequent career has largely allowed her to be beautiful, it does take courage to spend most of her screen time in an unflattering hi-vis stab vest, perpetually tired and occasionally bruised and bloodied. Lancashire unapologetically wears Sgt Cawood like a second skin. She has said, “They’re endurance tests, really. I think the whole thing is draining, simply because of Catherine’s disposition. She wears her emotional state of mind everywhere. There’s always the weight of it. It’s great to play.” The first scene of the first series sets out Happy Valley’s stall. It opens with a remarkable two-minute monologue where Cawood scarcely draws breath. Bulky in her hi-vis and utility belt, and weary – she has seen all this before – she faces Liam, a young man high as a kite who is threatening to set himself on fire in a children’s playground. It reaches its climax with the apparent non-sequitur of: “I’m Catherine, by the way. I’m 47, I’m divorced, I live with my sister who’s a recovering heroin addict. I’ve two grownup children – one dead, one who don’t speak to me – and a grandson, so.” Liam says: “Why don’t he speak to you?” “It’s complicated. Let’s talk about you.” The police radio crackles that the main thing is to “keep the subject engaged in conversation”. “Yeah,” her colleague says drily. “I think we’ve got that covered.” We know already where we are not. From the off, Wainwright and Lancashire signalled loud and clear that their trademark style will be to wrongfoot us, to confound our expectations and to make us love Cawood. Over three series, she has made us share her pain, she’s made us laugh out loud, she’s made us howl in outrage. And it’s all been done with deft masterstrokes. Really, the pair of them have been every bit as manipulative as villainous Tommy Lee Royce. That’s why the show’s massive audience has been talking about nothing else for the past week. The speculation about the possible endings have ranged from “everybody dies” to “alien abduction” (plus my own preferred option of “off to the Himalayas in the Land Rover with Alison Garrs”), and that speculation is a measure of what great writing and masterly performance can achieve. We don’t see it nearly often enough on our screens. Bob Dylan is a massive fan, apparently. I can’t wait for his next album and The Ballad of Happy Valley. Or maybe even Catherine Cawood and the Wankatron Twat. Val McDermid’s 1989, published by Sphere, is out now.