‘I do love a bit of blood and thunder,’ Tony Parsons confesses. ‘Gore doesn’t put me off. And I like to know the proper way to slit a throat. It’s not some drunk hacking and chopping away at a neck; there’s a clinical, far more efficient way to do it.’ No, this has nothing to do with Parsons’ admission back in May that he is a UKIP supporter. The multi-million selling ‘men lit’ novelist and Sun tabloid columnist is talking about his new line of work: the much less sinister business of writing crime fiction.

Although his political views could seem all the more gruesome in light of this recent career shift, he’s at pains to point out that, really, he’s just a fitness-obsessed family man who has buried himself into the world of homicide detectives, autopsies and forensic pathology. All in the name of researching a new character, Detective Max Wolfe, star of his first crime novel, The Murder Bag.

Parsons, the ex-husband of Julie Burchill and one-time punk reviewer at the NME, may be more famous for writing loosely autobiographical relationship dramas such as Man and Boy and Man and Wife, but as a reader he always enjoyed following in the crime footsteps of serial heroes like Inspector Rebus, Philip Marlowe and James Bond. ‘Someone like Jack Reacher is an amazing character; he’s the ultimate man alone. I liked the idea of creating a character that defends the weak, but is also rooted in reality, someone with domestic responsibilities and everyday duties. So Max Wolfe is single parent to a five-year-old daughter, with a dog to look after.’

It may be an unexpected left-turn in the writer’s career trajectory but, to him, it’s the best of several worlds. ‘There’s still plenty space in crime fiction to talk about what I want: politics, relationships, being a man. If anything there’s even more freedom. Doing all that in the context of a thriller makes it exhilarating for me.’ So, as Wolfe scours blood-splashed crime scenes and visits the Metropolitan Police’s homicide division in its real-life HQ at 27 Savile Row, Parsons finds the space to drop in his commentary of London life.

‘London is my town and my neighbourhood,’ says Parsons, who grew up in a council house in Essex, the son of a Navy commando and a dinner lady. ‘A lot of people don’t know there’s a massive police station right there in the West End. I like the idea of all these tourists walking around and eventually thinking of Max Wolfe in that part of town. We live in a time of incredible conspicuous privilege, which I don’t remember seeing before. So I wanted my writing to reflect that, and feel totally contemporary. After all, Raymond Chandler wasn’t writing about some retro, vintage version of Chinatown, he was writing about modern LA as he saw it.’

Meanwhile, a bit further along the shelf of your local crime fiction aisle, possibly filed under Tartan Noir, is Blood Whispers, a dark exploration of Glasgow’s criminal underworld. It’s a grizzly tale of human trafficking, corrupt CIA officers and violent Serbian gangs. A face glares out from the book’s jacket; the author is dressed in black, with a shaved, scarred head. But wait, the face is familiar: it’s wee Gregory, the lanky schoolboy of Gregory’s Girl fame!

‘Yeah, of course, when I first started writing crime fiction, all everyone wanted to talk about was my acting, but that made sense,’ says Sinclair, who is a warm and candid interviewee. In fact, when it’s time to drive to pick his girls from school, he insists on putting the phone on speaker and continuing our chat about his painting, Scottish politics and books that make readers cry.

He’s in his 50s now, married and living in Surrey, a stay-at-home dad to two daughters, yet still being asked to recite lines from the film he made back in 1981. ‘I knew I had to throw some punches if I was going to shake off the nice guy image and be taken seriously as a writer.’ Blood Whispers is the follow-up to Seventy Times Seven, Sinclair’s crime debut, a tale of contract killing and torture set during The Troubles. It was a labour of love he wrote without any book deal, because it just seemed like a good way of escaping the acting world.

‘I’d drop acting tomorrow if I could pay the mortgage,’ he shrugs. ‘Acting is really nowhere near the same thrill for me as writing. Most people get depressed when they don’t get a job; I get depressed when I do get a job!’ Still, he’s had some high-profile gigs, including acting alongside Brad Pitt in World War Z, and award-winning musical theatre roles in The Producers and She Loves Me (later adapted into the film, She’s Got Mail), and is returning to his hometown this November to play Jeeves at Glasgow’s Theatre Royal. But clearly, acting doesn’t get his juices going the way that writing does now.

‘It’s not the same thrill for me at all. I remember first going up to Edinburgh for the Book Festival [in 2012] with my first book, and they introduced me as an author. I’d never felt a thrill like it. It sounds wanky, but painting pictures in people’s heads is amazing.’ His first book went down well and was praised as an assured debut, which definitely took the pressure off.

‘It was a far better reaction than I’d ever hoped for, so that gave me a bit of confidence. I certainly didn’t suffer from “difficult second album” syndrome; this one felt much easier than the first. I think my wife [Glaswegian Shauna McKeon] used to think I sat in the corner, staring out the window all day. I kept telling her I was thinking. Basically, the writing has legitimised my daydreaming.’

Tony Parsons, Charlotte Square Gardens, 0845 373 5888, 9 Aug, 7pm, £10 (£8).
John Gordon Sinclair, Charlotte Square Gardens, 0845 373 5888, 17 Aug, 8.30pm, £10 (£8).