The man who could be the first black 007 drapes his lithe body lazily over two couches in a hotel suite in London. He is shoeless in all-black with one cashmeresweatered torso splayed across an armchair, while his sock-clad feet perch on the lip of a neighbouring, small stuffed couch.

"No Bond questions, please," a publicity agent from BBC tut-tuts two hours before the interview with British actor Idris Elba, 43.

Rumours have been heating up over the past two years, with fans urging movie producers of the secret agent franchise to sign on the suave black actor for the role now embodied by Daniel Craig.

But Elba is to talk about his small-screen life in crime instead. In particular, the fourth season of the detective series set in London, Luther, which premiered in Singapore yesterday on BBC First (StarHub TV Channel 522), a subscription video-on-demand service.

The hit show, which debuted with Elba in the lead role in 2010, sees him return in two 90-minute-long episodes.

Playing detective and deejay

"We wanted to bring the character back to life again," he says.

"The show - people think it is over from the last season, but it's not. He's a man who has moved on from the place and he's found peace. But it's inevitable that he goes back to work."

In the hiatus from his outing as the dark, agonised police inspector, the actor has been busy playing Nelson Mandela in Justin Chadwick's 2013 biopic Mandela: Long Walk To Freedom, the demigod Heimdall in the Thor movies, and apocalypse fighter Stacker Pentecost in Pacific Rim (2013).

On April 21, he returns to the big screen again as CIA agent Sean Briar in the thriller Bastille Day.

"I think Luther just needs a break. That's where you meet him. He needs to nourish himself. I think considering what he does for a living and who he is and how much bad luck he has, his karma needs time," Elba says of Luther.

But "he sits still and all he can think about is all those people trying to get away with murder".

This time, the crime that brings the British detective back from licking his wounds after the deaths in Season 3 of his teammate Ripley (Warren Brown) and, gasp, his serial-killer muse Alice (Ruth Wilson), is a cannibalistic serial killer who leaves gory evidence of his crimes across a bleak London-scape.

"It's like Gotham City. It is London. It is a character itself in the show," Elba says.

In between questions, he pauses to eat from a can of Skittles, insisting on offering you a few pieces of the coloured candy. He shifts and adjusts his weight, but never relinquishes his premier position in the room as the resident graceful, all-observing slouch.

Elba's long engagement with the grittier facets of the underworld predate Luther and Bastille Day, however. In fact, most viewers will be familiar with the actor's outing as drug kingpin Russell "Stringer" Bell in acclaimed HBO series The Wire, which he revealed he had unintentionally prepared for by running a short sideline career pushing weed in his less salubrious days as a club doorman in between acting jobs.

The whole era, including The Wire, Elba says, is "over for me… I've moved on to a new part of my career".

As John Luther today, he says: "I'm not having to create a human being to become John. I can use my accent, my size, I'm from London. All those are contributing to my character.

"But with Stringer or Mandela or any other character, I put on an accent, different syncretic behaviour. But John Luther is one character. I'm a workaholic, John's a workaholic. We have big hearts. He's forward-thinking, I'm also like that… maybe a bit more chilled out."

In Bastille Day, however, he puts back on an American accent and trades some of the fabled British grit for tight sweaters to leap nimbly across rooftops. The movie, which also stars Game Of Thrones' Richard Madden, is set amid a terrorist-stricken Paris, eerily pre-empting last year's tragic Charlie Hebdo killings in the city and, more recently, the attack in Brussels.

But "the film is about good vs bad in the city, completely different from what's going on in our own world", Elba cautions.

"That's not to say we as filmmakers are insensitive to the nature of violence," he adds, "considering we made this movie before what happened in Paris."

The tough guy is clearly the smoothest - and one of the most silver-tongued - actors in Britain and he knows it.

Someone asks about the recent controversy over the Oscars ignoring black actors and he raises an eyebrow.

"I have no opinion on the Oscars," he says with a smirk.

Aww. Come on.

"The truth of the matter is you're looking at the flower," he finally says, somewhat cryptically. "The problem is something that begins at the roots."

Raised in London's East End, Elba is the son of a Ford factory worker from Sierra Leone and a Ghanaian clerk. He has a one-year-old son with make-up artist Naiyana Garth and a teenage daughter from one of his two previous marriages.

Growing up, he says he spent a lot of time "fighting off people".

"Not because I was a big guy, but because of the colour of my skin. In a way, it helped train me for all the action movies."

Quite apart from dubious work on the grubbier streets of inner cities, however, Elba had once upon a time fixed tyres in a car assembly plant and moved equipment for a relative's mobile wedding disco business.

The after-school moving job eventually parlayed into a fullfledged parallel career in the music industry, where Elba has gained a reputation as a bona fide deejay by the name of Big Driis. Every year, he still spins at parties in Ibiza.

"My downtime is, a lot of time, still spent working. My greatest time is when I'm making music in the studio," he says, pausing and offering this reporter another Skittle.

You are on the verge of asking the no-go question on Bond (rumours are that studios found him too "street" for the dandy killer role). Instead, you ask where Luther will go via Hollywood - there is talk that an American version of the British TV project is in the works, with Elba in the team not as an actor, but as a producer.

"I don't want to be in it. I just want to be on it," the actor says.

"It means I get to keep the integrity of the show, from someone who's part of the DNA."

That said, he is eager to assure everyone that he remains in the market as an actor - Bond or no - alongside producing and spinning.

His acting career began via a scholarship to the National Youth Music Theatre in the 1990s, which saw him applying his skills quickly in Crimewatch re-enactments on TV. Soon, he was inching his way into small parts in British police dramas The Bill and Inspector Lynley.

Over the years, the mounting experience in the cop TV and film genres has led him to become an unlikely expert on what he calls "the procedural aspect of detective work".

He says: "In our show, the villains are calculated as hell. I realise that the successful villains are always the calculative ones, not those that go boom boom boom!

"They're silent, quiet and damaged. They come in all shapes and sizes.

"That just made me more sensitive to looking at people. I'm a good judge of character, but you can never ever pin someone down to good or evil, you have to see what they do to you."

Another Skittle comes my way, this time with a wink, Elba multitasking with a creeping glance at a babysitting PR agent.

"Go on, take it," he says with all the cool, slick charm of one not quite a spy on Her Majesty's Secret Service, but a dude in a cashmere sweater who could be wearing a leather jacket outside a Soho club.

"It's only a Skittle. You know you want it."

•Luther is available on BBC First (StarHub TV Channel 522) and Bastille Day opens in Singapore on April 21.