Mike Craven wanted to mark the moment his bestselling books about murder and mayhem in the Lake District had done well enough for him not to need to go back to work in the Probation Service. But rather than cracking open a bottle of Champagne, or looking for a new car, he added to his eclectic collection of tattoos.

Sitting down to discuss his blistering new thriller, Fearless, of which more shortly, he shows me his inked fingers, seven of which bear intricate symbols, each relating to one of his books – including one he hasn’t even started writing yet.

“I got to a point about 18 months ago, when I thought, ‘Even if I don’t sell another book, I’ve made enough money and I’m close to my pension now’,” he explains.

“Getting finger tattoos was my way of saying, ‘That’s it, I’m a professional writer’. Even if my publisher doesn’t want book seven, they’re getting it because now I’ve got the tattoo!”

Frankly, it seems highly unlikely any publisher would turn him down.

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With his shaved head, muscular physique and tattooed arms and hands, the former soldier turned chief probation officer for Cumbria – who writes as M W Craven – admits he makes an unlikely literary superstar. But he is one, nonetheless.

His award-winning novels featuring one of the unlikeliest pairings in thrillerdom – misanthropic detective Washington Poe and high-functioning civilian crime analyst Tilly Bradshaw – have won legions of fans, inspiring everything from a blend of coffee to five-day holiday excursions to his Lake District locations for foreign tourists. The 55-year-old memorably describes his books, now published in 26 countries, as “locked-room mysteries with added sarcasm”.

His most recent, The Botanist, is shortlisted for the prestigious Theakston Old Peculier Crime Novel of the Year, supported by the Daily Express, and Craven
will be one of the big draws at the world-famous crime writing festival in Harrogate next month.

But, as he is at pains to explain today, his entire career, from long before he started writing, has been a fascinating mixture of accident, luck (sometimes bad) and instinct.

“I’m like a twig on a stream just bumping into things,” he smiles.

Growing up in Newcastle, the son of a cigarette salesman and a nurse, Craven joined the Army on a whim, going to the recruitment office with a friend (his pal decided against it, while Craven joined the Royal Electrical and Mechanical Engineers).

Then after 12 years, he left the army by accident, when discharge papers were mixed up in a bundle of documents, quitting that afternoon. Later, he went to university to study social work after realising it was a two-year degree rather than the usual three.Having been a welfare officer in the Army – “If someone was feeling suicidal, they were supposed to come and talk to me, which obviously never happened, because that wasn’t the culture then” – he “fluked” his way onto the course.

From there, again by chance, he joined the Probation Service and worked his way to the top in Cumbria where he eventually took redundancy as chief probation officer when the service was privatised for a short, mostly disastrous, period.

But it was a brush with death aged 35 from a kill-or-be-cured cancer 20 years ago that really changed his life when he was rushed into hospital with abdominal pains.

“I went in for a biopsy. It was December 17, 2003, I remember because I had tickets to the opening of the third Lord of the Rings film,” he says.

“I was obsessed with the book and the films I thought were just excellent. I thought I’d be a bit sore, but I’d still make it to the cinema.

“It was under a general anaesthetic and, when I woke up 12 hours later, two teams of surgeons had removed my kidney, my bowel and other bits of me to remove a tumour the size of a rugby ball.”

A biopsy revealed Craven was suffering from an incredibly rare cancer, Burkitt lymphoma, normally found in the jaws of children in Africa. Following the op, he needed three rounds of chemo but, after the first, surgeons admitted it hadn’t worked.

“Within a week, the tumour had regrown to the size of a tennis ball,” he continues.

Craven was told they now needed to explore palliative care options, and his family began to plan his funeral – “it was gonna be on a Monday apparently, I found out recently” – but then a sliver of bone from his hip, removed for tests, revealed the cancer hadn’t spread as expected.

Suddenly the gruelling treatment was back on and Craven was, incredibly, cured. He left hospital six months later and several stone lighter, but alive and in remission.

And, in a bizarre twist, because his cancer was so large and rare, nearly every big research hospital in the world subsequently requested samples. “Basically, my tumour has travelled further than me, and it’s in more countries than my books are,” he tells me. “There are slices of it all over the place.”

Having gone back to work in the Probation Service, his mortgage paid off by critical illness cover, he lasted another 11 years before taking redundancy to write full-time.

“I said to my wife, ‘I’ll give it three years, and if it’s not working, I’ll go back. I’ve got a social work qualification, I can get a job in a week’. She said, a year. I said 18 months – so we compromised at a year.”

Having published two Lake District-set novels already, he began work on The Puppet Show, the first of his Poe and Bradshaw thrillers. Signing a TV deal kept him ticking over financially as book sales crept up, mainly via word of mouth.

The action follows a series of gruesome murders, each taking place in one of the Lake District’s stone circles, not well-known but among the UK’s most stunning.

Like fellow bestselling author Elly Griffiths, whose novels featuring forensic archaeologist Ruth Galloway have become synonymous with Norfolk, Craven’s books have made him Mr Lake District. So why set them in Wordsworth Country?

“Cumbria isn’t just a beautiful county; it’s an interesting county and it has everything a crime writer needs – picture-perfect villages and beautiful mountains and lakes. Marshlands and forests; coastlines and heavy industry,” he explains. “It has significant pockets of poverty and it has affluence. It has a population of just 500,000 but gets 20 million visitors a year. In short it has conflict.

“Also, it doesn’t have saturation CCTV and mobile phone coverage is spotty, so I’m able to ignore the tools city cops use in favour of more old-fashioned methods – getting off your a**e to knock on doors.”

Having “jumped off a cliff without a parachute”, there’s little doubt Craven is soaring as one of the stars of crime writing.

Much of that is to do with Tilly Bradshaw, his compelling on-the-spectrum computer whiz whose nerdy, naive optimism acts as a foil to Poe’s crankiness.

“Poe’s a character readers recognise, he’s a bit grumpy, a bit Harry Bosch, a bit John Rebus,” he says. “Tilly, I need to explain or new readers won’t get her.

“She’s a once-in-a-generation mind who was expected to spend her whole life in academia but rebelled and took a job at the National Crime Agency without ever having worked in the real world.

“There’s a wide-eyed naivety about her. Plus, she’s a social hand grenade because she’s spent a life in pure maths, and maths doesn’t lie, so she’s painfully honest.”

Does he make use of the sensitivity of readers, I wonder? After all, creating such a memorable character who appears to be autistic could be risky, couldn’t it?

“I trust my instincts,” he says.

“When I was doing social work training, I did a placement at a school for the autistic. Although I’ve never said whether Tilly’s on the spectrum or not. Readers can make up their own minds.

“The NCA is a real-life unit, it’s mainly for psychologists, but I made it my own because I wanted to have a team that could go all over the country. When my book contract came through, it was for a crime series set in Cumbria. So for every book I’ve got to find a reason why they come back here.”

All of which brings us to Craven’s latest blockbuster, Fearless, which couldn’t be further from the Lakes if it tried.

Originally titled A Man Apart, he wrote it in the early noughties before tackling Poe and Bradshaw. Its hero, Ben Koenig, was an elite US Marshal, hunting the bad guys, before a bullet injury to his head rendered him immune to fear. As Craven explains: “I once worked with a guy who had an acquired brain injury. He couldn’t regulate heat so even on a cold day, he’d be drenched in sweat.

“That led me down a rabbit hole of research which revealed a disease of the brain which, 99.9 times out of 100, results in people becoming hyper-sensitised to fear – everything scares them.

“But in incredibly rare cases, it’s the other way – they have no fear at all. I thought it was a great concept. Five years later I used it in my book.”

Having dug out his manuscript during lockdown at the request of a publisher, after some serious polishing and reworking, Fearless sparked a bidding war among producers and is currently heading towards the small screen via a major streaming service.

Early book reviews have been positive, though some critics have noted a similarity in the opening – in which Koenig is arrested in a diner – to Lee Child’s debut novel, Killing Floor. One suggested, tongue-in-cheek, it should be titled “Shameless”.

“It was a tribute to Lee, really,” says Craven. “The diner was my nod to Killing Floor, then I went my own way.” While he’s still waiting to hear what Child thinks, he’s looking to catch up with the Jack Reacher author at the Theakston Old Peculier Crime Writing Festival next month in Harrogate where they are both appearing.

I wonder if he’s nervous? No more than usual, he admits. “Lee is one author I still get tongue-tied in front of because I’m such a huge fan. He has got an iconic character and the premise is superb. But his writing is just magical, it’s like poetry. He’s incredibly eloquent, very funny, he’s kind of my hero.”

Craven and his wife, Joanne, currently live in Carlisle but are looking to move to the countryside so they can get a dog.

I suggest the Lakes.

“The reaction to my books has been fantastic – I get invited to speak at the university, at the Round Table, at the WI and community groups. I’m even recognised which is nice but weird – particularly when people ask for selfies in supermarkets, pubs and even toilets,” he smiles.

“It’s a lovely part of the world to visit, but it can be tough living there.”

You might even say it can be murder, especially in M W Craven’s books.

• Fearless by M W Craven (Constable, £16.99) is published. Visit expressbookshop.com or call 020 3176 3832. Free UK P&P on orders over £25. The Theakston Old Peculier Crime Writing Festival takes place July 20-23. Visit harrogateinternationalfestivals.com for more information.