Fake tanning isn't a topic you expect to be discussing with Nicholas Hoult, and yet here he is happily expounding on the pitfalls of a spray tan.

“Me, Colin (Firth) and Matthew (Goode) were staying in the same hotel and we had to apologise because we’d wake up and there would be brown sheets,” says Hoult, recalling the beauty treatment he and his co-stars underwent while shooting Tom Ford’s 2009’s stylish drama A Single Man.

No, he didn’t wear the usual paper pants for the procedure but apparently they did use Ben Stiller’s tanner – “so I felt really honoured”, he says, smiling.

It’s 11 years since Hoult appeared alongside Hugh Grant and Toni Collette as a young boy with a chronically depressed mother in About A Boy.

Now aged 23, he’s one of the country’s most exciting exports, having starred as Eusebios in Clash Of The Titans and Hank McCoy, otherwise known as Beast, in the X-Men prequel X-Men: First Class.

Next is the 3D adventure Jack The Giant Slayer in which Hoult plays the title character.

Based on the fairytale Jack And The Beanstalk, it’s an all-action caper about an age-old war that’s reignited when the young farmhand Jack unwittingly opens the gateway to a fearsome land of giants.

“I remember the story from the pantomime version but it’s changed a lot in this,” says Hoult, who cuts a tall, slim figure in his jeans, jumper and leather jacket.

He’s also wearing a sports cap that he later removes to reveal a shaved head for his role in the new Mad Max movie.

“I feel exposed but I kind of like it because I feel free as well,” he says of his shorn look.

At least he has the features to pull it off.

As his ex, the Oscar-winning actress Jennifer Lawrence (the pair met on the set of X-Men: First Class and dated for two years before splitting recently) has remarked, Hoult has no idea how good-looking he is.

“It was very nice for that person to think that – their opinion only though,” he says, clearly embarrassed.

Hoult describes Jack as a have-a-go hero. “He feels useless but bad things happen to him even when he’s trying to do good,” he explains.

“Throughout the story, he faces some of his fears and then manages to save the day.”

And Hoult’s own fears? “Spiders,” he says immediately. “I’d scream and hide but I have to pretend I’m not terrified because I’m a guy,” he admits laughing.

He’s not a fan of heights either, which was both a help and a hindrance during the shoot.

While much of the action was filmed against a green screen, a huge chunk of the magic beanstalk was built for the actors, including Ewan McGregor and Stanley Tucci, to climb.

“I did some climbing practice but my character’s not supposed to be a great climber and he’s scared of heights, so I didn’t have to look like an action hero,” says Hoult.

“It was like being in The Borrowers,” he says. “There was a giant kitchen, so I was running around with massive knives and chopping boards and there’d be bushes as herbs.”

Acclaimed filmmaker Bryan Singer, who also directed The Usual Suspects and the original X-Men movie back in 2000, helms the film.

“It’s fun working with him because he’s a very intelligent guy and knows how to tell a good story,” says Hoult, who reveals Singer has been waiting years for technology to reach a point where he could make the movie he’d envisioned.

This included bringing the giants to life through motion capture. “There’s a really sinister tone to the giants because they’re being played by real actors, like Bill Nighy,” says Hoult. “They’re very human, fast and intelligent and that kind of changes the ball-game.”

Hoult first met Singer at the read-through for 2011’s X-Men: First Class, which Singer wrote and produced.

“He mentioned he was doing this film but then I was supposed to be making Mad Max,” reveals Hoult. But then Mad Max was delayed, so he could sign up to play Jack.

“It’s stressful,” says Hoult of playing the title role. “Luckily as an actor you’re not holding the whole production together, but I feel the pressure definitely because you’ve still got to try and put in a performance that’s maintained to the high level.”

About A Boy was his big breakthrough but Hoult had been acting since he was eight and, bar a stint at the Sylvia Young Theatre School, has learnt his trade on set.

“I’ve got good memories of all the jobs I’ve done because I’ve worked with great people,” he says. He doesn’t watch any of his movies back, though. “Maybe one day when I’m sitting in a rocking chair, I’ll get the grandkids over and make them watch them all,” he says, laughing again.