SITTINGdown with actor Aidan Turner is a slightly uncanny experience. I’ve come to our interview from a screening of the final instalment of Peter Jackson’s Hobbit trilogy, The Battle of the Five Armies, in which the 31-year-old Dubliner plays orc-slaying dwarf Kili.

In the film, he has long hair and a prosthetic nose and wields an exceedingly pointy sword. So it’s a shock to encounter him in a dapper black suit, a guitar perched on his lap (the hotel where we meet is so agonisingly trendy the rooms are furnished with musical instruments). The look is more Urban Outfitters than Mines of Moria.

“Making those movies seems like quite a long time ago,” he proclaims, setting the guitar to one side. “We started four years ago and wrapped a year and a half ago. Returning to the stories and anecdotes, it feels incredibly distant. You move on to other things; revisiting the past can be strange.”

Amid a cast of literally hundreds, Turner is arguably the breakout star of The Hobbit. Going into the project an unknown he was handed the juiciest character arc, that of a dwarf who falls in love with an elf. In fusty Middle Earth the slow-burn flirtation between Kili and Tauriel (Evangeline Lilly) verges on scandalous — as conceived by director Jackson, the pair are heroic fantasy’s very own Romeo and Juliet, their relationship doomed from the outset.

The Kili-Tauriel romance does not exist in Tolkien’s chaste original novel. Jackson created the storyline to add humanity to a trilogy that otherwise risked boiling down to endless fights and chase sequences (certain critics have argued the movies remain exactly that). Because Jackson shoots far more footage than he could ever use, Turner had no reason to suspect Kili would become so prominent: for all he knew, his scenes with Lilly could have ended on the cutting room floor. It was a pleasant surprise to discover this was not the case.

“Peter shoots hours and hours — seven or so per film, then cuts it down to two and a half. When I saw the last Hobbit movie [2013’s The Desolation of Smaug] and how big my storyline was I thought, ‘Bloody hell, that’s really nice’. I thought they were going to cut me — they didn’t.”

Turner has no idea whether Jackson wrote the Kili storyline with him in mind and demurs when it is pointed out he is by far the most charismatic of the dwarves accompanying hobbit Bilbo Baggins to the Lonely Mountain and the treasure of the dragon Smaug.

“I hope this doesn’t make me sound like an a-hole but everyone gets their moment. I had no idea my part would be as big as it was and am really proud and super happy. It wraps the films up for me in a really cool way. Did Peter plan it from the start? I have no idea: he was constantly working on the screenplay. You’d get back to your room after a long day and one of Peter’s assistants would knock on the door with a new script for the next morning. If someone had stolen the original script at the start of the shoot it would not have made any difference — there were so many changes along the way.”

There’s a feeling that The Hobbit, shot over 18 months across New Zealand’s ruggedly handsome South Island, could make an A-lister of Turner. He was already a household face in the UK by dint of his part in supernatural drama Being Human (he played a dashing vampire).

However, The Hobbit has catapulted him to an entirely different level: outside of key protagonists such as Gandalf (Ian McKellen) and Bilbo (Martin Freeman), Kili is one of the few characters Jackson took the trouble to properly flesh out.

“It was a very strange experience,” says Turner. “You’d walk onto these huge sets — you might have a scene where you had to run in and say ‘The orcs are coming’. Everyone was looking at you: Ian McKellen, Martin Freeman: all these heavy-hitting actors waiting.

“And maybe there’s a bunch of extra running down a hill and 20 horses galloping in another direction. So you might dash in and you mess your lines up — just fluff them entirely. You’re going ‘Oh s**t, all these people are watching’. The extras would have to go back into position; the crew would have to walk the horses back — all so you could do it again. It’s quite a lot of pressure.”

Some of the tasks he was required to undertake pushed the definition of ‘acting’ to its limits. Laughing, he recalls the occasion he and actor James Nesbitt (Bofur the dwarf) were airlifted to the top of a desolate mountain and told to run as fast as they could as a helicopter filmed from overhead.

“Andy Serkis [Gollum in the earlier Tolkien movies] did a lot of the second unit directing. He’d take the actors to some peak nobody had set foot on for centuries: you were given a sword and told to run. Me and Nesbitt would be standing there chatting and then you’d hear the rotor blades and you’d think: ‘Here we go’.

“You had to get it on as the helicopter came over the top of the mountain — you’d hear Andy before you could see him. You wondered ‘What am I doing at the top of a mountain in New Zealand, holding a carbon graphite sword, wearing a prosthetic nose and running as fast as I can?’ It was quite surreal.”

The shoot was gruelling, with the younger actors expected to know their way around a battle-axe. Stunt-men were on hand for the really tricky stuff — nevertheless, the cast received lots of bumps and bruises, and dispensed a few of their own too.

“I remember fighting an orc — he was this really nice New Zealander, wearing a green bodysuit [so the CGI details could be added later]. I swung and accidentally struck with the butt of my sword. I thought nothing of it and was delivering a line of dialogue. Then, I noticed red coming from under his mask. I’d broken his nose. Things like that happened all the time: on another occasion, the dwarves were up a tree, flinging pine-cones at the goblins. We had all these stunt guys hanging on wires. We noticed they’d all nodded off. The wires had wrapped around their legs and cut off the main artery that is responsible for circulation.”

Turner speaks highly of Jackson, describing the director as understated and humble. With so many demands on his time, the New Zealander couldn’t be one of the gang exactly — yet was at pains not to be aloof and unapproachable.

“He has to orchestrate so many different departments. You think of the director as this guy manning the camera, talking to the actors. Peter is so much more. He’d be in his tent, on this battered old armchair he’s had since the Lord Of The Rings, and there would be a line of people with stuff for him to sign off on: costumes, sets, everything. He had to juggle a great deal.

“However, when you were talking to him about a scene or your character, you felt you could have asked him anything. He’s extremely affable — a humble individual and not at all a huge personality. The atmosphere on set was extremely calm. That may be hard to believe if you’ve seen the films. But that’s how it was: calm and enjoyable.”