Neil Cross: "I'm always having ideas for Luther – even when I’m doing the washing up"

Various solar conditions mean that the planet is to be incinerated in just five years' time, and shadowy government forces are trying to stop the obvious panic that knowledge of this will cause.

The drama is also very violent, opening with two shocking scenes from the off and never shying away from brutality throughout the opening episode (a new BBC1 Saturday night trend it seems, if this, Tom Hardy drama Taboo, and Kit Harington's Gunpowder are anything to go by).

But however dark his TV dramas, Cross in person is as affable, thoughtful and as gentle a man as you could possibly hope to meet.

“I enjoy frightening people – it’s a higher calling, " laughs the Bristol-born writer who lives in New Zealand with his Kiwi wife and their two young children. “Voluntarily being scared while at the same time being safe is a great feeling. I’m a huge fan of all things horror.

“I don’t like torture porn or anything like that and I don't write about what I want to do to other people. I write about what I’m scared other people might do to me.”

The world of Hard Sun is frightening, yes, but it’s fascinating to watch two cops who are mortal enemies facing the end of everything they hold dear.

It's really a drama about character and Cross found the Renko and Hicks relationship so intriguing he first conceived of them without the apocalyptic storyline, focusing instead on the troubled Renko’s undercover quest to expose her counterpart’s dodgy policing methods (which she works towards at the start of the drama before their lives are turned upside down).

He has also sketched out a five-series arc for Hard Sun – what he jokingly calls a “Stalinist five-year plan”. But he insists that he is not going to cheat viewers over the central end-of-the-world premise. “I didn’t want to give myself a way out and I haven't,” he says. “We end [series one] on a moment of revelation.”

It would be tempting to ascribe a deeper meaning to the drama's theme of global catastrophe, given all the world’s current anxieties. But Cross says he started writing the show before Trump and Brexit and has “got nothing to say with a capital ‘S’…or messages to impart.

“But given the way the world currently is, and given what feels like an uncontrolled skid into an unguessable future, that sense of global anxiety is going to feed into the stories,” is his assessment.

Cross, who is 48, is now avowedly committed to writing dark and entertaining drama, thrillers with punch and momentum.

Early in his life he had toyed with literary fiction, working for a publisher and publishing various literary novels of his own including Always the Sun (2004) which was longlisted for the Booker Prize.

He has written one of three planned Luther spin off novels (The Calling), but don’t expect him to return to the world of literature any time soon.

“Most commercial thrillers are horrible but so are most attempts at literary fiction,” he notes. When probed he adds: “I don’t like novelists. I had to spend a lot of time with novelists when I worked in publishing. And as a breed I find them tiresome on the whole.

“There’s novelists whose company I greatly enjoyed. But sit me down with someone who writes for the screen and that’s always a pleasure because people who write for the screen spend their entire working lives being beaten up.”

Like many people, he also thinks that TV is the supreme cultural force in the world, as well as the main provider of entertainment.

“You can see how television has been liberated to become the moral instructor that the novel was in the mid to late C19th. Starting with The Sopranos.

“Part of my rejection of ‘literary fiction’ is an acknowledgement that high quality long-form television has culturally stolen its clothes.

“Name a novel, literary or otherwise, that has achieved the same kind of cultural influences as The Wire? In the last ten or 15 or 20 years? The Wire is a masterpiece. Regardless of medium it’s a narrative masterpiece. In the last 20 years no novel has come close."

So it’s no wonder that he’s sticking with TV. Indeed, January 2018 sees filming begin on another Luther story, told over four episodes.

After the upcoming series, he's also loathe to rule out any more Luther – “every time we say we’re ending a few months go by and we all just miss it."

“I’ll keep writing Luther until Idris or I drop off the perch,” says Cross who does, however, rule out a return for Rose Leslie’s sidekick DS Emma Lane (though intriguingly, he refuses to deny the possibility of seeing more of Luther's intriguing sociopath associate Alice Morgan, played by Ruth Wilson).

“And as long as Idris and the BBC are up for it then so am I. I am always having ideas for it, even when I’m doing the washing up I will think of something... I have learned my lesson with Luther to never say it’s the end.”

Or the end of the world for that matter…

Hard Sun starts on BBC1 on Saturday January 6 at 9.35pm