Running is the only form of exercise that I enjoy. I used to do 10ks and half marathons, but now I just run for my head.

Tips? I think you have to learn to enjoy it. I don't run with music because I think you've got to clear the mind. I run with my dog.

I'm a frustrated musician. That's what I wanted to do, before I got side-tracked into acting. I was in a band when I was young and we were offered a record deal, but it was a bad one and my brother was only 16, so we turned it down. My parents were like "it could ruin your life".

My desert island record? I can't do that man, it's too hard! Recently I co-curated a music festival in Cork where The National and Bon Iver played. I love those guys.

My ideal holiday is with my wife and kids, in west Cork. You can't go wrong anywhere on the West coast of Ireland. Beautiful beaches, great boozers, and the people are brilliant.

New York is probably my favourite city, but I wouldn't go there on a holiday.

After a role, there is a sort of deep compression period. I think it's important to take a break. With Tommy [Shelby], it tends to be quite immersive and you disappear [into him] for four months. It would be foolish to go straight into another job after that.

It's hard work, and it should be hard work. I hate moany actors.

Dunkirk was an amazing experience. Mark Rylance is a lovely, lovely man. He's got a gorgeous energy and presence, and obviously he's a sublime actor as well. I think he's top of his game, now.

Style? I like to wear well-made, well-cut stuff, but I'm not a fashionista by any means. I'll have things that I like, but it's never a statement.

For me, an item of clothing doesn't become yours until you've worn it for a number of years, until you've imprinted yourself on it. I'll wear the shit out of a jacket, or a pair of boots or whatever. I love things that are naturally distressed.

I'm not a very physically-imposing presence, so everything I did at the beginning [of] was to try and give Tommy that sense of respect and authority, and capability. The haircut was part of it.

Of course, I've watched all the classic gangster films. But Peaky Blinders is so inherently British, so we weren't aping any American thing.

The best age to be? The age you are, I guess. That's what everyone says, isn't it? I really like being middle-age. There was no sense of panic at turning 40, I've got a lot more common-sense now than I had when I was 21.

When I was a young actor starting off in the theatre, we were in our dressing room at the end one night and I just took off my costume and put it on the chair. One of the old actors I was working with said: "hang up your costume, always hang up your costume". It wasn't the specific piece of advice, but what it represents that has stuck with me. Even though you're the one out there under the lights, there are a huge amount of people working to get this stuff made and they are equally important as the actors prancing around.

I'm a big reader. I never read anything other than novels. At the moment I'm reading Mrs Osmond by John Banville, which is his sequel to Portrait of a Lady. It's brilliant. It's John Banville camouflaged as Henry James - it's very, very interesting.

I was always obsessed about the Great American Novel. I read John Updike's Rabbit series recently, all in a row. He's an extraordinary writer. You read those books and you realise that's what people are trying to do in television, now. You spend time with that guy Rabbit from when he's like 20 until he's like 65 or something, and it's fucking mad.

A Peaky Blinder film? I think Steve [Knight] has some ideas. You'd have to be careful, but I'd be curious to do it.