Add The Marlow Murder Club to your watchlist

Death in Paradise mastermind Robert Thorogood has some words of advice for any actor who gets the call for a role in the drama: “If you want to have a good time on the show, be the corpse. Fly to the Caribbean, lie down for a couple of hours, then go scuba diving for a week.”

To the naked viewing eye, it doesn’t look as though his job as show creator and writer was much harder: a body discovered in some glamorous villa or a beach club; wives, lovers and sulky assistants suspected then dismissed; sleuth has a Eureka! moment, murderer revealed, all in time for drinks down at Catherine’s Bar. Easy peasy? Do not be deceived, Thorogood warns us.

“I’d put money on it being the hardest TV to write,” he says. “You have one hour to kill someone at the start, catch the murderer at the end, reel off the denouement, so that’s 20 pages of script spoken for before you get to the fun stuff. It’s hard to get the balance and tone right, the complication of the mystery, the warmth of the characters, make the detectives loveable but still good at their jobs…”

Exhausted, Thorogood quit writing his Caribbean crimes after 11 series. Now, adapting his own Marlow Murder Club books for screen, he stipulates that each episode lasts a Morse-like two hours: “I wanted a middle-distance run, not a 100-metre dash.”

In a chaotic world, it’s lovely to go somewhere for vicarious thrills

Given the success of Death in Paradise, following Thorogood’s original pitch for “British copper in the Caribbean solving a murder every week against his wishes”, plus its equally snug spin-offs Beyond Paradise and Return to Paradise, along with many other stablemates – Grantchester, Agatha Raisin, newcomers like Ludwig and Death Valley, the genre’s “Big Daddy” Midsomer Murders – we clearly can’t get enough of this type of mystery. But what exactly is “cosy crime”?

“It’s a tonal thing,” says Thorogood. “People are killed, but with a relatively clean method of dispatch, and you barely see the body. We take the murders seriously, but characters tend to be heightened, an entrepreneur or a fading rock star. The world is dialled up, which keeps it frothy and fun.”

So why the enduring appeal? “In a chaotic real world on fire, it’s lovely to go somewhere for all your vicarious thrills, skullduggery and betrayal, posh people all lying and cheating, in beautiful but confined spaces.”

It’s impossible to discuss cosy crime without mentioning its queen. Thorogood read and re-read Agatha Christie’s books as a child, enthralled by her “magic tricks, and her wit. Poirot is a very comical creation.” To this day, he follows the same rules she set.

“You must play fair with the viewer. There’s always the moment when the detective solves the crime. At that moment, the viewer should be able to press pause, play along at home, and solve it too. Second, the killer has to be caught. Closure and justice served is critical. And third, you always need a scene with Harry the Lizard. You tie yourself in knots to create the mystery, and then Harry steals the show.”

Even for Thorogood, there’s one that got away. “I would have loved to have been the first person to come up with The Murder of Roger Ackroyd. It’s maybe not Christie’s best, and doesn’t play fair with the reader, but imagine the moment she had that idea.” I’m no Poirot, I’m not even Jim Bergerac, but I somehow knew he was going to say that one. Cosy Caribbean duty surely calls.