Jamie Dornan: 'I'd like to stop tying women up'

Whipping boy … Jamie Dornan. Photograph: Debra Hurford Brown/Camera Press

Acting is a strange way to make a living, but you can pick up all kinds of skills on the job. In recent months, for example, Jamie Dornan has become particularly good with knots. When we meet in London he is on a break from filming a second series of The Fall in Belfast, in which he plays a serial killer who ties up his victims. Before that he was in Vancouver filming the big-screen adaptation of EL James's Fifty Shades of Grey. Dornan plays the lead, Christian Grey, a man who also practises a bit of rope work, though in his case, as part of consensual S&M. In fact, the only time Dornan has been able to stop the tethering in 11 months of relentless filming has been playing Abe Goffe in Peter Flannery's Restoration drama, New Worlds.

Two years ago, Dornan was a member of one of entertainment's most derided subspecies, the actor-slash-model. A boy from Belfast who'd struck it lucky and wound up working with Bruce Weber and Calvin Klein, he had always wanted to act, so went to the US for pilot season: LA's annual casting meat market – the recollection of which, he tells me, makes him feel physically sick."There are a couple of classic knots I know now," says the 31-year-old, "and I've put them to good use far too many times recently. In fact I'd like to do a job where I don't have to tie women to beds."

Expecting to book more love interest roles in chintzy dramas like Once Upon a Time, he was instead called back to audition for The Fall in the UK. Allan Cubitt's startling script turned out to be BBC2's biggest drama launch in years, largely thanks to the warped ying and yang of Gillian Anderson as a frosty detective set against Dornan as Paul Spector, caring therapist by day, rapist and murderer by night. Dornan has a natural, fidgety intensity – "a doctor once told me I have abnormal levels of adrenaline in my system" – and in The Fall he showed that he could twist the same pent-up fervour that was sexy in a Calvin Klein campaign into something deeply unnerving. Last month his performance earned him a Bafta best actor nomination.

No knots … Dornan, centre, in New Worlds

Meanwhile, British actor Charlie Hunnam, who had been cast to play Christian Grey in Fifty Shades of Grey, pulled out, and Dornan replaced him, awaiting whatever slings and arrows EL James's adoring readership will lob at him when Sam Taylor-Wood's film is released early next year. There is also the small matter of a one-year-old marriage, to the singer Amelia Warner, and a five-month-old daughter.

"I'm tired. I'm tired," he says, reflecting on a "mad year, professionally, personally". At times his tiredness verges on delirium. At one point he rails against the practice of restaurants putting lemon slices in Coca-Cola, unsolicited ("You can't deny it changes the flavour"). Then he catches himself and starts fretting that he sounds like a la-di-da Hollywood star.

Next week he'll be back in his hometown, to continue filming The Fall, which means once again transforming himself from a loving father into a psychopath. The key to Spector's menace, and quite possibly what won Dornan that Bafta nomination, was that he chose to make his cold-eyed killer a loving father, too. Allan Cubitt had been adamant that, though this was a character with young children, he didn't – or couldn't – love. Dornan thought differently: "I thought, he's still got to talk like a dad – that is still his daughter, no matter what the audience see; in those moments he's still a father talking to a daughter. I guess that makes it all more unpleasant because you see that he is human and can show love."

Dornan chose right – in Paul Spector he has kicked off his career with an indelible bad guy, the perfect calling card for an actor on the rise. It must feel like something close to vindication for the actor-slash-model looking to lose the slash.

"I never felt I was trying to prove anything apart from to myself. But I come at it from a funny angle. Although it looks like I've only been acting a few years, we're talking hundreds and hundreds of failed auditions. I look back on it now and I don't know how anyone gets through the rejection." It was the modelling that allowed Dornan to fail so persistently. "I was lucky. If I hadn't been getting paid to model I definitely would have stopped. I would fly off, do a shoot here and there, get paid well, then go back to preparing – and failing – for auditions and meetings."

I wonder if being such a high-profile model was what stopped him breaking through sooner. There's a funny thing about achieving international renown in your pants – people aren't apt to let you forget it. "I think I've done two shoots in my underwear ever. They both happened to be for Calvin Klein. But that tag – underwear model – I just can't get rid of it. And it's such a bizarre, specific thing – underwear. It's like I never modelled clothes."

A killer and a dad … Dornan in The Fall. Photograph: Steffan Hill/BBC

It didn't help that someone – he thinks it might have been a fashion editor at American GQ – gave him a nickname, and it's stuck. He says he is "haunted" by the moniker "the golden torso", not least because the very mention of it means that any discussion of his acting is inevitably accompanied by a picture of him in his pants, again.

If anything will shake off the tag it will be Fifty Shades, but he says, "I don't think I'm allowed to say anything mate", when I try to talk about the one thing that everyone will want to talk about when they talk to Jamie Dornan until its release in February. Plainly, Dornan finds this omerta about his first blockbuster role a little exasperating but, he explains, it's all part of the contract and "the pressures of a big studio, a big thing". So we'll have to wait and see: it could be the Ishtar of soft porn; it could be his own Shame.

Of the attention he's received for his first big Hollywood role, he says: "The whole thing's ridiculous." Then he falls silent. "It's just all a bit silly the way it works. Another pause. "I think I could lose my mind." By contrast, coming back from Fifty, as he calls it, straight on to The Fall and Belfast, "felt like coming home, in the loveliest way".

But he does appreciate that it's only a combination of the two – the industry behemoth and the critical darling – that has enabled him to get offered better roles and be pickier about them. "Right now I don't need to work if there's nothing that I want to do. I've done three jobs back to back. Let's see how they are received. If there's nothing I want to do, I'll just play golf and change nappies."

• The final episode of New Worlds is on Channel 4, 22 April, at 9pm.