Line of Duty, it's safe to say, is a cop show with a difference. For years, television's maverick detectives have flouted the petty regulations that real coppers must live by - but in this drama health and safety rules rule, OK.
"On TV, detectives ignore procedures and protocols because what matters is catching the bad guy," says Line of Duty writer and producer Jed Mercurio. "In the real world of policing, if you don't play it by the book, then the bad guy gets off, and you get disciplined. I think we're bringing the police drama up to date."
Take for example episode three, which builds up to an epic car chase. It could be any primetime cop show: Lennie James and Neil Morrissey's detectives are in a sleek, black, unmarked car hunting a mysterious cellphone signal through a warren of quiet London streets. Suddenly a 4x4 lurches past.
James, who plays DCI Tony Gates, hits the lights and siren, accelerating off. You sit back, grip the cushion and wait for the action. And then…
"Health and safety," Morrissey's DC Nigel Morton pipes up. "This is not a designated pursuit vehicle." So Gates drives round a corner, parks and continues the chase on foot while Morton phones through for back-up. As you can imagine, things don't go well.
"Gates is in a situation where he has a personal stake, is not a trained pursuit driver, is driving an unmarked vehicle - albeit with blue lights - and he is in a tactical phase of a pursuit," Mercurio says, with a sly grin. "For all those reasons, ACPO [Association of Chief Police Officers] regulations demand he should discontinue the pursuit."
He calls Line of Duty a "revisionist's take" on modern policing. Ostensibly it's about an internal investigation. Clean-cut DS Steve Arnott (Martin Compston) is transferred off firearms and onto AC-12, the Met's anti-corruption unit.
He's soon ferreting around DCI Gates's super-clean arrest record, convinced no cop is that good in real life. Gradually it becomes clear that Gates has an unfortunate past and a very contemporary problem - but it's far nastier than anyone expected. Vicky McClure's DC Fleming, Neil Morrissey's DC Morton and Gina McKee's scheming businesswoman Jackie Laverty are all sucked into a black hole of betrayal, suspicion and murder - each one contributing a little more dark matter as their own problems implode.
The cops spit jargon, mock each other and indulge in a little light sexist banter, so that you're briefly reminded of Gene Hunt and the Ashes crew. But as the interweaving plots knit closer together, Mercurio sets the thriller against the bureaucratic hazards of a modern copper's working life.
We see hapless officers prevented from chasing suspects by rules insisting they stay near their vehicles. We see arrests for mugging rejigged to make it look as if knife-crime figures are falling. We even see officers sprawled over armed response vehicles, signing off health and safety and risk assessment forms in the final seconds before an armed unit breaks down the door of a suspected terrorist.
In other words, it's part thriller, part satirical swipe at the red tape, form-filling and health and safety culture so hated by the likes of Sun columnist Richard Littlejohn and police bloggers such as Inspector Gadget and PC Copperfield whose online accounts of perverse bureaucratic processes became successful books and inspired Mercurio's feisty script.
"When I was researching the script I think there was a general view among police officers that you have to jump through hoops, whether you're investigating a minor case of shop-lifting or you're looking at a very serious crime.
"It's a world I think anyone outside the police would be shocked by - and, importantly for me as a dramatist, I think most people are so unfamiliar with it that it stands out from all the other police dramas. There's always a cop drama on screen, but I don't think there's anything else like this on air.
British thriller writers, he explains, are divided into two camps - the country house murder writers, and the dark psychological thriller writers. He, on the other hand, loves gritty urban shows like The Wire, but admits the British public don't share his tastes - on the BBC, the Baltimore crime drama's ratings peaked at around 600,000.
"The real juggernauts that have stayed and kept an audience year after year are in the vein of Morse and Midsomer Murders," he sips from his coffee cup meditatively. "Ultimately, I think that's a reflection on the shows that have found an audience rather than necessarily what programme makers have been trying to do.
"My tastes are fairly mainstream. I watched The Bridge. I liked The Killing. I love The Shield. And that's always the issue - everybody wants their programme to be seen by the biggest audience. But sometimes you want to make something that is stylistically very distinctive and pushes the boundaries. That means the chances are that fewer people will enjoy it and you reach the point where you have something that is admired but largely unwatched. So you're always trying to find the balance."
He skirts the issue of similarities between The Shadow Line - the BBC2 stablemate of Line of Duty shown earlier in the year. That drama also featured a black cop being investigated for corruption and drew critical plaudits but relatively poor ratings. All he'll say, diplomatically, is: "Well, both shows have the word 'line' in the title…"
Perhaps that's a fair place to stop the comparison. After all, Shadow Line's creator Hugo Blick came up through comedy, while Mercurio is in his element exposing the dark side of the public services.
His debut drama, Cardiac Arrest - which first went out in 1994 while he was still working as a doctor - dumped political correctness in the morgue with scenes of junior doctors smoking, drinking, hating patients and their job, and indulging in some fairly fruity racist and sexist backchat. Nurses gossiped and schemed, hospital managers were paper-chasing jobsworths and almost everyone tried to sleep with almost everyone else. Of course it was a huge hit, and propelled him into a TV career almost by accident.
"I was on course to be a member of the Royal College of Physicians before Cardiac Arrest," the 46-year-old grins. "But I think my experience working in public service completely informs my writing, how I portray hierarchies and insinuations and the expectations thrown up by the public - along with a whole other range of expectations and restrictions that are placed on them by the bureaucracy that runs their lives."
Does that mean he thinks police red tape has to go? "I think, as a citizen, that if a police officer breaks the law there should be a system in place that brings them to account," he begins carefully. "Having said that, I do think that bureaucracy has taken up far more time than anybody expected it to.
"But I think there's a wider thing going on in public services, a much wider thing. You see the announcement of the GPs' medical strike, the police officers marching in protest at job cuts… it's a phenomenon that's gathering momentum, with people who do high-pressure, responsible jobs. They're used to making decisions, being listened to and getting their own way on a day-to-day professional level.
"Whether you agree with their point of view or not, the BMA and the Police Federation are the people that can make things happen. What the long-term outcome of both of those issues is I don't know." He smiles, and the writer is back in the room. "But we have plans to do a second series, and it would be great to keen an eye on that."
The beat goes on... cop dramas coming soon
The Good Cop (BBC1): Warren Brown is a Liverpool police officer whose ideals are tested after the murder of a friend. Does he let colleagues handle the case or take justice into his own hands?
The Fall (BBC2): Gillian Anderson is a senior cop brought in from the Met to catch a serial killer (Jamie Dornan) terrorising Belfast.
A Touch of Cloth (Sky1): Charlie Brooker's screenplay, which stars John Hannah and Suranne Jones, is a parody of every police drama ever written.
Line of Duty begins tonight on BBC2 at 9:00pm