Writer-director of In Bruges and Seven Psychopaths, Martin McDonagh is one of the UK’s finest filmmakers. His latest effort, Three Billboards Outside Ebbing, Missouri, is the story of Mildred (Frances McDormand), the mother of a murdered teenager. After months without any progress on finding her daughter’s killer, Mildred puts up three billboards publicly challenging the local sheriff (Woody Harrelson) on his lack of success. As funny as it is painful, it’s one of the frontrunners for Best Picture at this year’s Oscars.
You’ve been sitting on this idea for years. Where did it start?
I was on a bus going through one of the southern states [in the US] when I saw two billboards in a field with [a message similar to Mildred’s]. I thought it was angry and painful and despairing, calling out the cops. It flashed past me and that idea stayed in my head. About eight years ago I decided I wanted to put pen to paper. Once I decided it was a mother who’d put those billboards up, Mildred just jumped out and ran off down the road with a hand grenade.
You wrote this with Frances McDormand in mind. What would have happened if she’d said no?
There isn’t anyone else who could play Mildred. There isn’t anyone with that same integrity and forcefulness, or someone who can play a working-class woman without being patronising about it… Thankfully she said yes. We’d have been in trouble if she hadn’t.
Why did you write it for her?
I met her when [my play] The Beauty Queen of Leenane was on in New York. I met Frances and Joel [Coen, her husband] just after the show, for a few seconds. Then I met her again about five years after that. I said we should work together, do a play together. She said, “No, not a play. A film.” There are just people who I want to write for. I didn’t write for her because she told me to. I would have done it anyway. All the power was on my side.
And how did you work together?
I thought she would be tough and she was! I knew she’d be a take-no-prisoners kind of person. That can go two ways. I hoped the performance and the integrity of that would be the most important thing to her, and it was… She’s very strong-willed, as am I. I’m pretty pedantic about sticking to the script and making sure it’s all word for word. I’m not really open to messing around with that. Neither is she, to a degree, because she’s got a strong theatre background. But she’s also playing the lead character in this and I think – there was a five percent disagreement about certain bits of dialogue. It was less about adding things or changing things and more about taking things away. Even that I’d take umbrage to, because that’s what I’m like.
You’re not up for improvisation then?
I like actors a lot but because the writer is the first one to get kicked in the head on a film, I’m very defensive about that and I won’t let it happen. I’m really protective about scripts. If I get wind of an actor not being cool with the script then they’re not going to get the job.
That’s why I work with the people I work with. Not just because they’re theatre people but because they know you’ve done your job and they respect that.
You’re in the mix for the Oscar race. How do you feel about that expectation?
You don’t want the film to just go under the radar and die, like In Bruges did in America. Who knows what will happen, but the awards talk is something I’ve never had before… We finished this in January  and even then I was thinking, “I can’t believe anyone’s going to be better than Frances this year”. So you want her to be part of the awards conversation. And Woody, too. It’s nice for yourself, too, of course!
You already have an Oscar, for your short film Six Shooter. Does that make you more relaxed about the attention?
Definitely. When I was nominated for Best Screenplay for In Bruges, I had a relaxing, fun time, because I had one already. And I knew I wouldn’t win, which made it even more relaxing!
What do you remember of winning?
I remember being completely terrified and really concentrating on not falling over on the way up the stairs. My mate who was in the film was supposed to be my date for the ceremony, but he got stopped by immigration and sent home, so I was determined to say thanks to him. That got me through the nerves a little bit but I was still terrified. I remember walking off and thinking, “Phew, that’s done and I’ve got an Oscar now”. So instantly there’s a joy to it. The fear and the nerves are gone.
Your brother, John Michael McDonagh (The Guard) is also a filmmaker. Do you give each other advice?
Haha. Never. We like all the same films and grew up loving the same films, which is why we’re in this game. But I’m big-headed about my stuff and he’s big-headed about his stuff, so we don’t care. We don’t ask an opinion.
Three Billboards Outside Ebbing, Missouri is in cinemas from Thursday February 22.