Matthew Lewis: Having played the same character in Harry Potter for 10 years I jump at every opportunity to mix it up

While Matthew Lewis prepares for our interview, his PR gives me a warning: “Don’t call him Neville Longbottom.” Lewis, aged 26, made his name in Harry Potter playing the unfortunate stooge but this is the year he will finally shake off that reputation, with roles in two TV shows and a major film. Of course, it helps that he no longer looks anything like the clumsy boy wizard.

When Lewis revealed his newly ripped body to the world by posing topless on the front of Attitude magazine’s June 2015 issue, he received so much attention that he had to turn off his phone for three days. The worst comment was from Harry Potter author J K Rowling, he says. “She told me, ‘I’ll fully support you in everything you do, but next time keep your clothes on’. That was awkward.”

Today he is fully clothed, sitting cross legged in ironed jeans and a new white shirt. We are at the Soho Hotel to discuss his role in Ripper Street, the Victorian crime series that has been resurrected by Amazon Prime, as well his turns in police drama Happy Valley, and the film adaptation of Jojo Moyes’s novel Me Before You, out this summer, in which he plays a triathlete.

This year’s roles appealed because “they were totally different”. “Having played the same character for 10 years I jump at every opportunity I have to mix it up. Going away to do Harry Potter was a bit of a ballache,” he continues in his deadpan Yorkshire accent, before realising this could sound brattish. “Don’t get me wrong, I sound like a twat. It was such an opportunity and there’s me going ‘I want to go to the pub with my mates’. That feeling disappeared. I realised I was doing an incredible job.”

The low point was when Helena Bonham Carter accidentally burst his eardrum with a wand and “it really hurt”.

Lewis has been acting since he was five, following his older brother Anthony, who is also an actor, and has appeared in Casualty. They now live together near Alexandra Palace (“further north than Jeremy Corbyn’s constituency”).

“I assumed everyone acted when they grew up,” says Lewis. “I copied my brother on everything he did so I fell into it. I don’t remember deciding I wanted to act. My parents encouraged but never pushed.”

His mother is a magistrate and “hates courtroom drama, she tears them to pieces”, and his father is a “happily retired” computer engineer.

The Harry Potter actors were paid millions for their roles — is it difficult for Lewis to remain motivated with that cash behind him? “I’d probably get to about 25-years-old and run out of money. I try to be sensible. I’m from Yorkshire and stuff, so I’m a real tight git.” He won’t even pay for Amazon Prime, he jokes, and has been asking the Ripper Street crew if he can have a free account.

He’s in touch with the Harry Potter team, speaking to Robbie Coltrane on the phone and playing cricket with Tom Felton, who played Draco Malfoy. “I would never in a million years regret doing Harry Potter. I owe so many things in my life to it,” he says.

But he doesn’t know about the forthcoming two-part Harry Potter play, set to open in June, and says “wowzer” when I tell him about it. After Potter finished he did a play “to learn my craft” and it took him four months to be given a good review: “I hadn’t appreciated there would be paying customers and it was a f***ing job. Suddenly I was out of my depth.”

Ripper Street appealed because, Lewis says, “I have a morbid fascination with serial killers. This show is about dramatic human stories that happen to be set in Victorian England. The first episode deals heavily with imperialism, immigration, Islam, murder, police corruption and all these things we are still talking about today. Man’s inhumanity to man is an interesting topic.”

Happy Valley is another police story, set in the present day but again with “horrible people doing horrible things”. The first series won critical acclaim for Sally Wainwright’s writing and Sarah Lancashire’s performance as a determined policewoman. He isn’t allowed to say much about it other than he plays “a wayward soul” called Sean.

“Without sounding like a wanky actor, it was one of the toughest challenges I’ve ever undertaken. I had to go to some pretty dark places. I was strung up really tight.”

After that he had four months to get in shape — on a strict no carbs or alcohol diet — for Me Before You, which also stars Game of Thrones’ Emilia Clarke and Sam Clafin. He trained with Tim Buckley, who works with Daniel Craig on James Bond and is “simultaneously my hero and the worst person I’ve ever met in the entire world because he flogged the shit out of me”.

He did high-intensity weights, circuits and ate a high protein and fat diet. “The idea of training was more about form and thinking about muscle groups — but when you are on set with Emilia Clarke there’s little need for other motivation to get in shape.” He’s mostly stuck to Buckley’s regime, except he had a Dr Pepper today and spilt it on his white shirt.

When Attitude asked to put him on the cover, “I was like ‘Why the hell do you want me?’ Naturally you think of cover models to be David Beckham or someone insanely handsome, not me. But I’ve worked with the photographer, Joseph Sinclair, before and he is incredibly talented. He suggested some more risqué shots because I was in the best shape of my life and I trust him. Of course I was self-conscious. Even if one day I end up looking like f***ing Chris Hemsworth I’m never going to not be self-conscious.”

He was allowed to check the photos before they went to print and says they were “half decent”. Months later he is sent a copy of that picture every hour on Twitter and doesn’t have a copy of the magazine because, “I’ve seen enough of me in pants to last a lifetime”.