"When I got the part of Bill Weasley in Harry Potter, I was so excited to be in the film that I googled it and just saw this barrage of comments saying, ‘He’s not good-looking enough to play Bill Weasley!’ And I said, ‘You know what? I’m not going to do this again.’ I kind of agreed with them though!”

I marvel at his jovial tone – were hundreds of people to disparage my looks online, I doubt I’d be laughing uproariously while broadcasting the fact. Most likely I’d be huddled somewhere in the foetal position, simultaneously sobbing and eating trifle with my hands.
“Ah, it’s alright, people feel like they have ownership over the characters because they’ve paid money for the book, so they can imagine the characters how they want. As long as they pay money for the movie too, it’s fine. But I shouldn’t have gone looking – don’t listen at a door if you know people are talking about you, you’re just asking for trouble! It was my own fault – and a very good lesson learned!”
Gleeson’s current role in the dark comedy Sensation is unlikely to cause him any such problems. He’s already been widely praised for his performance as Donal, an introverted Tipperary farmer who strikes up an unlikely relationship with a prostitute. His combination of subtle tragedy and awkward comedy is an acting masterclass, but it’s his other, more – ahem – personal techniques that may come under scrutiny. Featuring some graphic sex at which Donal doesn’t exactly excel (we’re encouraged to stress that this aspect of the character bears no resemblance to the actor’s own experiences), how did the 28 year-old feel about inviting friends and family to a film whose opening shots see him furiously masturbating in a field?
“Ah, it’s nothing they haven’t seen before!” he jokes. “To be honest I read it and thought it would be really funny. Obviously some scenes – the blowjob one in particular – are a bit more full-on, but I was up for it. Years ago when I wrote for Your Bad Self, the sketches I wrote were about me having sex with a horse and stuff, so I can’t exactly plead innocence in that sense! Sex and sexuality is interesting and complicated – particularly for Irish people, because historically we’ve had a complex, guilt-ridden relationship with it. But it’s also bizarre and messy and funny and I think you have to show the comedy side of it. And playing it on set – dropping your kaks in front of the crew or putting on a tiny thong to keep yourself contained – if you can’t laugh at that, you’re done.”
Gleeson’s comic ability will come as no surprise to fans of the actor’s father Brendan, who’s built a career on his unrivalled ability to seamlessly transition from intense drama to outrageous comedy in films like The Guard, In Bruges, Breakfast On Pluto, Harry Potter and I Went Down, to name but a few. But though it may come innately to the young star, laughing at sex is not something Ireland is known for. In the past decade alone, films like Song For A Raggy Boy, The Magdalene Sisters, Sinners, Evelyn and Conspiracy Of Silence have all addressed sexual abuse in the Catholic Church. But Gleeson feels that modern attitudes towards sex are ripe with complexities waiting to be explored.
“Obviously we address prostitution in this film, but there’s also a really interesting generation divide in Sensation. Donal never got any sex education because his parents’ generation didn’t talk about sex. So he can’t talk about it, hasn’t had it, but on the other hand it’s everywhere because he’s grown up in a world where porn is readily available. It’s just two interesting extremes of Ireland’s relationship with sex – generations’ relationship with sex – both of which are wanting.”
The actor’s observational eye and writing experience meant that a foray into directing was inevitable, and his award-winning short film Noreen, starring Brendan and Briain Gleeson, will air on television this Christmas. But Gleeson seems reluctant to declare firm intentions to step behind the camera full-time.
“It’s just that, well, every actor says that, don’t they? And then they never do. But working with the Coen brothers and Tom Hall for this and now with Joe Wright for Anna Karenina, I find watching what they do, the passion they have for it and how they translate that into making exceptional films and inspiring great performances fascinating. So we’ll see. But for now I’m just really happy to be doing what I love, being able to play these great characters and find the beauty and craic in their lives. And mine I guess. I’m pretty damn happy at the moment. Or maybe it’s just because I’ve been kind of immersed in my role in Anna Karenina, it’s just Levin’s energy!”
He pauses.
“So it’s probably a good thing we didn’t chat while I was filming Sensation, you could have walked in and found me wanking in a corner!”

Sensation hits cinemas on November 4.