In the 1920s detective story writer, editor and literary critic Father Ronald Knox laid down his Decalogue: the ten golden rules of detective fiction. They included such pearls of wisdom as “Not more than one secret room or passage is allowable”, “All supernatural or preternatural agencies are ruled out as a matter of course”, and the unforgettable, “No Chinaman must figure in the story”.

Since then no-one has thought to revisit the rules — though many have ignored them — but now Mark Billingham, best known as the author of the bestselling, award-winning DI Tom Thorne series, is taking over BBC Radio 4 Extra’s Saturday morning schedule to present his Rule Book of Crime. In it he’ll be delving through the radio archives to draw out what makes the greats of crime fiction so enduring and whether there’s some formula for creating successful detective stories.

While he may be interested in poring over classic detective stories to better understand the tropes of the genre, there are no strict rules that Billingham himself follows while writing. The most important “rule” he will abide by is more an intention: to write the most entertaining story he can, trying to keep the pages turning and engaging the reader quickly. In the past that would most probably have been achieved through a puzzle element to the story, but nowadays Billingham thinks that is not enough:

“If there's a murder mystery element, trying to solve whodunnit is part of it, but it's no longer the be all and end all. If your book is spoiled by the people working out who the killer is, it's not a very good book. Firstly because they shouldn't work out who the killer is, but also there should be something else going on.”

That something else could be a psychological mystery. So you have a whydunnit instead of a whodunit. Or it could be a game of cat-and-mouse between the killer and the detective which takes the hero to places where they, and the reader, may not feel that comfortable, to the extent that it becomes hard to empathise with the detective’s methods. That’s something that Billingham particularly enjoys.

“It’s nice to mess about with those expectations as to who is the good guy and who is the bad guy. I’m of the opinion that they [detectives] don’t always have to be heroic. Possibly he has to be heroic at the end, but in getting there he may do things that readers don’t like very much.”

It’s an aspect of his work that addresses an issue of wider concern within the genre: the ubiquity nowadays of the flawed detective. Many critics complain of constantly reading or watching troubled tecs, with a secret in their past, a drink or drugs problem, failing family relationships. Billingham gives such complaints short shrift.

“As crime writers we put these characters, year after year, book after book, through the most horrendous trauma, dealing with grief and death and loss and violence. We can’t pretend that these things don’t affect these characters, they have to. If they don’t then you’re essentially writing cartoons.”

He points to what he feels were the unrealistic emotional responses of many classic creations from the golden age of detective crime fiction. Detectives such as Hercule Poirot, Miss Marple and Lord Peter Wimsey were able to deal with death with little more than a shrug of the shoulders and a shake of the head.

“[They’d] dust themselves down, put on a clean jacket and a new boater and be fine again.”

Despite these complaints he knows just how important writers of the golden age are in the canon of detective fiction. Though he readily admits that Agatha Christie is not his favourite author, he recognises that she changed the game for ever when she made the lead detective the killer. He also cites the more hard-boiled American masters Raymond Chandler and Dashiell Hammett as writers who affected great changes. But the greatest respect is afforded to Sir Arthur Conan Doyle, not least for the fact that his detective was so flawed.

“Over a century ago you're talking about a detective who's completely dysfunctional, who can't have relationships, problems with drugs, with a love of music. All the things that modern detectives are accused of.”

He sees this as a vindication of the current crop of flawed crime-solvers, that things haven't changed very much since Holmes – and the popularity of BBC1's Sherlock would seem to bear this out, that people like off-kilter genius. He sees the flaws within a sleuth as almost a genre expectation.

“If you were writing a western and you decided that your cowboy wasn't going to have a gun or a horse or a hat, then fine, but he's probably not a cowboy. There are certain boxes that you do have to tick.”

Though he likes to put his creations through the emotional wringer in a way that would strike a chord with the reader as being realistic when confronted with trauma, he knows his books aren't truly grounded in reality, but in a sort of heightened version of it.

“As a writer you're making a pact with the reader, you're saying look, I know and you know that if this book was really a murder investigation it would be a thousand pages long and would be very dull, and you would be very unhappy with the ending.”

The characters in a Mark Billingham book may be troubled, but he does not go to a great amount of effort to create a back story or a carefully annotated past for them. Something he found has its advantages and disadvantages when writing about DI Tom Thorne.

“In some ways I've made a rod for my own back because you forget. On each book, I'll sit there going, what colour are his eyes again? But the strength of it is that I'm discovering new things about him all the time at the same time as the reader. The character stays unpredictable because you don't know what's going to happen; in truth I don't know what's going to happen. I'm glad I did that, even though sometimes I wish I did have that big file that will tell me the names of all his cousins and where he went to school.”

Two of his Thorne books have been dramatised (Sleepyhead and Scaredy Cat) on Sky1, with David Morrissey taking the title role. But Billingham has not got to the stage that Colin Dexter did with Inspector Morse, that he writes his most famous creation with its televisual incarnation in mind.

“It's a constant running joke between David and me, that I say, I don't think of you when I'm writing, and he says well, I don't think of you when I'm acting. The reason for that is that I've never seen Thorne's face clearly, because I'm inside his head, I'm looking out through his eyes. So I know what he's thinking, I know how he thinks, I know what his opinions are on things, but I don't really know or very much care what he looks like.”

The same loose way that Billingham forms an idea of his characters also feeds into the manner in which he writes the stories themselves. There is no set plan when he sets out, there is no outline or chapter plan. He may have an idea of the structure of the book and how it will finish and what will happen to the villain, but he's not quite sure how he will reach that ending.

“It’s like driving through fog at night. I know where I’m going to but I can only see as far as my headlights. It will be a pretty circuitous route, I’ll take a few wrong turns and get lost a couple of times, but I’ll get there in the end.”

That circuitousness may hint at twists and turns but Billingham is not totally enamoured of shock twists in crime fiction.

“When you think of a great twist, or a red herring, or a way of misdirecting the reader, it is good but you know that they are just tricks at the end of the day, and the way to keep interest is to write characters that people care about. That's when you've genuinely got suspense, because they know the sort of book they're reading, they know they're reading a book in which people die. If you get them to care about the characters from page 1 you’ve got suspense from page 1.”

That desire not to resort to cheap tricks leads this story to take a sudden turn to reveal that Mark Billingham does actually have rules for writing. It's just that those rules are not abstract proscriptions, rather an avoidance of things that annoy him as a reader.

“I read something and I think, oh I hate that, I hate that. Why did the writer do that to me? Therefore I pledge to not do that to my reader, so I guess the thing that you hate as a reader is to feel cheated. It's terribly easy to cheat the reader.”

More specifically, one of the things that is a great bugbear is the idea of the killer not being in plain sight – which, incidentally, is also one of Ronald Knox's cardinal no-nos – the killer needs to be there all the way through the book.

“You can't suddenly have the killer jump out of a cupboard in chapter 47 and go 'Ha ha, here I am!'”

Another specific bugbear is when the detective carries more knowledge than the reader, with Billingham arguing that a writer has to choose what to withhold. It's all about timing, choosing the time when to reveal those vital bits of information, but always playing fair with the reader. He describes an unpublished book he's just finished reading in which a character who is deeply traumatised by discovering a body at the start of the book ends up being the killer in the end. The illogicality of that made him want it to throw the offending book across the room.

“An unreliable narrator is one thing but that I just thought was cheating. I guess you just try not to cheat your reader, because crime readers are incredibly savvy and they read very widely. They know when they're being had over and they don't like it. So woe betide the crime writer who tries to do it.”

Talking of witholding information, the press release for Billingham's radio programme hints at a forgotten gem that the author discovered in the BBC archives. It teases that it was written by someone who'd worked on Z Cars and Softly Softly, and starred an actor from Cathy Come Home who also voiced a classic children's animation. When confronted with a guess that the writer is Allan Prior and the star is Ray Brooks, Billingham only admits that Brooks was the star.

He drops further clues that it was a cop drama that was actually produced by BBC Light Entertainment rather than the drama department, but claims he can't remember how long the show ran for (press information says from the late 70s to the mid 8os). The most he'll say is, “It's a cracking little bit of archive radio, and it's certainly something I hadn't heard before. It's terrific, it's a real little treat. It has this lightness of touch, which is interesting and makes it very listenable.”

When I admit that internet searches have come up with no results, the glee he feels at having hoodwinked another reader is hard to disguise.

“Ha ha, so you don't know what it is.”

And there the trail runs cold – until the big reveal on Saturday morning.

Mark Billingham's Rulebook of Crime is at 9am on Saturday 2 March on Radio 4 Extra