When I last interviewed Martin McDonagh, back in 2001, he mentioned that he had just started working on a play set in London “in that dark time just before and after they abolished hanging”. All he had to do, he said, was “get the story right”. Here we are, 14 years later, and the play, Hangmen, now set in Oldham, is just about to open at the Royal Court theatre, London, with David Morrissey and Reece Shearsmith in the leading roles. Did it really take him that long to get the story right?

“I guess I got sidetracked by other projects,” he says, as we settle in the corner of a bar near the Royal Court’s rehearsal space in Clapham. “But this was also a trickier play to write than the others. Before, I was writing from a blank page, but this is about a big subject – capital punishment and miscarriages of justice – and I really didn’t want it to be a message play. As always, I had to find the story and then let the issues just bubble up underneath. It just took a bit longer this time.”

Most of the action in Hangmen takes place over two days in a pub just outside Oldham in 1965, soon after parliament had announced the abolition of capital punishment. The landlord is Harry Wade, whose status as the second most famous hangman in Britain after the retired Albert Pierrepoint is something of a bugbear to him. (Wade’s name is an amalgam of two actual English hangmen: Harry Bernard Allen and Stephen Wade.) Like McDonagh’s other plays, Hangmen combines dark humour and spectacularly staged acts of violence. Unlike the Irish plays that made his name, though – the Leenane trilogy, The Cripple of Inishmaan, The Lieutenant of Inishmore – the banter of the locals is more restrained, though often just as tastelessly comical.

McDonagh describes this as his take on a “traditional comedy thriller”, but there are still moments of dreadful cruelty and elaborate violence. The plot turns on the arrival in the bar of a young southern stranger, Mooney (played by Johnny Flynn). His intent is never made clear. It is a tense drama, peopled with seedy characters moving in an atmosphere of English parochial repression, which unfolds inexorably towards a characteristically grisly denouement. A palpable sense of menace, made all the more potent by the claustrophobic setting, is sustained throughout in a way that recalls one of McDonagh’s great influences, Harold Pinter.

Reece Shearsmith in rehearsals for Martin McDonagh’s new play Hangmen. Photograph: Helen Maybanks

“Pinter’s early works were full of menace and caught that peculiar tension between everyday England and the darkness that often lurked just beneath,” says McDonagh, nodding. “There was certainly that tension in England in the early to mid-1960s. You had the Beatles coming up and, at the same time, there was still this Victorian practice of executing people – and sometimes innocent people. I wanted to explore that tension. Is it right to kill someone who is an evil man – or not, as the case may be – and what does that make the person who has to do it? Can they distance themselves from what they are doing? Is it nothing to do with them? And does it affect them?”

Hangmen marks McDonagh’s return to the London stage after a 12-year hiatus. In the interim, he followed up the extraordinary success of his Irish plays in America with the successful Broadway run of another baroquely violent play, A Behanding in Spokane, starring two of his favourite actors, Christopher Walken and Sam Rockwell. He has also made a name for himself as writer and director of two acclaimed feature films, the darkly comic In Bruges and the less cohesive Seven Psychopaths, in which Walken and Rockwell star alongside Harry Dean Stanton and Tom Waits, and which McDonagh now describes as “maybe a bit too meta”.

Did he find the switch from theatre to film difficult? “Well, put it this way, Hangmen is fun and relaxing after the films. Firstly, I had to become a director to protect the scripts. Seven Psychopaths wasn’t so bad, but In Bruges was relentless and exhausting. I had to deal with them [Focus Films, the production company]trying to change anything they could change. And Focus are supposed to be supportive, indie-filmmaker-friendly people. Scumbags. It was constant war, but they never won.”

Undaunted, he tells me he has written his next film, provisionally titled Three Billboards Outside Ebbing, Missouri and starring Frances McDormand, which he’s hoping will start shooting early next year. “It’s about a 50-year-old woman whose daughter is murdered and she goes to war with the police in her home town, because she thinks they are more interested in torturing black people than getting justice.” Though it sounds uncannily topical given recent events in Missouri and beyond, it was, he says, written “about four years ago”.

If anything, McDonagh’s absence from the British stage has helped burnish his reputation. “Every agent in Britain was kicking the door trying to get their actors in this play,” says Matthew Dunster, Hangmen’s director. “He’s very much an actor’s playwright. They all want to be in his work because they rate him as highly as anyone working today in theatre or film.” David Morrissey, who plays Harry Wade, agrees. “I would have killed most of Equity to get the part.”

What is it about McDonagh’s writing that inspires such respect? “His love of language,” says Morrissey. “You’re reading the script through with other actors and there’s immediately this incredible rhythm, like you’re batting words back and forth. That’s energising in itself, and then you start to pick up on the complexity of the script, all the underlying strands that are threaded through the play in such a subtle, revealing way.”

Ralph Ineson, as Inspector Fry, and David Morrissey as Harry, run through a pub scene in Hangmen. Photograph: Helen Maybanks

McDonagh, Dunster tells me, has been present throughout the rehearsals for Hangmen – “he even turns up for the circuit training and stretching exercises that the actors do every morning”. Is it not daunting to have the writer present while you are trying to interpret his work? “It should be, not least because he does have an alpha sense of his own worth as a writer, and that is exacting, but he’s also incredibly respectful and supportive. I think he’s really there for his own enjoyment. He loves seeing his work come alive.”

I ask Dunster if he senses a shift in tone in this play, a less heightened atmosphere perhaps? “Not really. He’s responding to the north of England rather than the west of Ireland, so the vernacular is different, but he nails it. There’s a precision to his writing and he has an ability to summon up this incredible sense of place purely out of his imagination. I’m actually from Oldham and he’s never even been there, yet Oldham is there, real and recognisable, in the play.”

Now 45, and looking tanned and even more dapper than his younger self, dressed in a dark suit and white shirt, Martin McDonagh has managed to confound the small but vociferous chorus of critics who dismissed his early work as shallow, vicariously violent and peopled with exaggerated-to-the-point-of-offensive Irish stereotypes. Many of the loudest voices against emanated from Ireland, where some journalists and academics also questioned his right, as an outsider (McDonagh was born in London to Irish parents and has both British and Irish citizenship), to anatomise contemporary Irish society in such a searingly satirical way.

“The less smart ones were set against me,” he says, grinning. “I think there’s still an undertow of that in Ireland: ‘Who the fuck is this English guy criticising us?’ They find it hard to take from someone who doesn’t actually live there. A lot of Irish journalists and commentators haven’t quite gotten to grips with the diaspora, that we can be as critical as people who live there.”

With the Leenane trilogy (The Beauty Queen of Leenane, A Skull in Connemara, The Lonesome West) and The Cripple of Inishmaan, McDonagh certainly had fun pastiching elements of traditional Irish theatre. His characters are both exaggeratedly rural and gleefully misanthropic, while the once-sacred bonds of home, hearth and family – as well as the faith and community – are ridiculed and mocked with an irreverence that was shocking and brutally funny. In The Beauty Queen of Leenane, a toxically co-dependent mother and daughter bicker and fight throughout, their animosity culminating in a shocking scene in which the daughter forces her mother’s hand into a bubbling pan of chip fat. In The Lonesome West, two brothers, one of whom has blown their father’s head off with a shotgun, torment each other relentlessly, while a hopeless alcoholic priest, who visits them to drink their poitín as much as to offer spiritual solace, drowns himself in a lake. In A Skull in Connemara, even the dead are denied their eternal rest, their bones dug up to make way for fresh corpses.

In all of this, McDonagh merged quotidian detail – local food brands such as Kimberley biscuits and Tayto crisps – with a heightened evocation of another rural Ireland unseen, or ignored, by the tourist board. As the Irish writer and political analyst Fintan O’Toole noted in 1999, “McDonagh’s Leenane is, at one level, still stuck in the 1930s. But that frozen, locked-in society has moved 40 years forward in time. It exists now at the fringes of a high-tech, postmodern Ireland shaped by media imagery, by multinational companies, and by tourism.”

That Ireland still exists, but it has been through traumatic times since we last spoke and, with the collapse of the Celtic Tiger economy, all has changed utterly. “Oh Christ, unbelievably so!” says McDonagh, shaking his head. “I remember people over there saying to me, ‘Why aren’t you writing about the new Ireland and the Celtic Tiger and how fantastic it all is now?’ Well, because it was a phoney pile of bullshit.”

Unbelievably, all McDonagh’s early plays, including the last one to be staged in London, The Lieutenant of Inishmore, a provocative satire on extreme Irish nationalists, were written in an intense 10-month long bout of creativity between 1994 and 1995, when, as he puts it, “I was sitting in my room without any real idea of what I was doing or where I was going.” Back then, the 24-year-old was writing, he says, “out of pure desperation”. Having left school at 16 and spent several years unemployed and adrift in south London, before landing a low-level job in the civil service, he promptly gave up that job to try his hand at writing.

“I didn’t have any big plan. I just knew I had to try something,” he says. “I remember, as a teenager, going home on a bus knowing that I was probably going to end up in a shitty job with some shitty boss telling me what to do and I had the Clash song, Clampdown, playing in my head. All the desperation and anger I had about my situation were reflected in those lyrics. The plays were written out of that sense of anger. It was Joe Strummer, God bless him, who inspired that anger, but also a love of poetic rage.”

Watch Colin Farrell and Martin McDonagh discussing the violence of Seven Psychopaths. Guardian

Almost simultaneously, McDonagh and his brother, John, now a successful writer and director of two feature films, The Guard and Calvary, were discovering the classic films of Martin Scorsese and Terrence Malick and hearing the raucous punk-inflected songs of the Pogues for the first time. So, by the time McDonagh started devouring Pinter’s The Birthday Party and JM Synge’s The Playboy of the Western World, he had already absorbed a range of disparate influences that would coalesce into a hybrid dramatic voice, both recognisable and new. And, like the Pogues’ Shane MacGowan, that voice was essentially a diaspora voice: crucially London-Irish rather than Irish, with all the rich, if sometimes conflicting, cultural baggage that carried.

“When I heard the Pogues, I connected with the songs immediately,” he says, “but it was also the first time I didn’t reject out of hand the kind of music that my parents had always tried to push on to us when we were growing up. They always tried to give us a grounding in Irish culture, whether it was learning to play hurling or listening to Irish traditional music. I suppose we pushed that away as you do when you’re young, but then the Pogues came along and articulated the London-Irish urban experience in a way that felt more real.”

McDonagh and his brother spent several summers in the west of Ireland as children, either in rural Sligo, where his mother’s family came from, or in Lettermullen, Co Galway, where his father grew up in an Irish-speaking community.

“Ireland was an idyllic place for us as children,” he says. “We had all these cousins and all this green countryside. Given what I’ve written about rural Ireland, my memories of it are all blue skies and endless play. I have a vivid memory of a Christmas spent there when I was eight or nine and all my Irish cousins still believing in Santa Claus. There was a sweetness and gentleness to that. It was something to be cherished and we were never to tell them otherwise. We weren’t cynical Londoners marooned in this alien rural place. We loved it there.”

In Elephant and Castle, the McDonaghs lived in a London Irish community with, as he puts it, “the Kellys on one side of the house and the Caseys on the other, and the Dubliners’ songs blaring out all afternoon.” His family moved up the road to Camberwell when McDonagh was still a child. When his parents returned to Ireland for good in 1992, he and his brother inherited the tidy terrace house near Camberwell Green. I went to a few parties there back in the early 2000s, having got to know McDonagh after interviewing him. What I remember most vividly is the interior of the house, each room immaculately tidy but decorated in a style redolent of another, older time. It was as if he and his brother couldn’t quite let go of its associations.

It was there that McDonagh found himself suddenly alone in 1994, after his brother went to Los Angeles on a screenwriting scholarship, and it was there that he started writing those first plays.

How was it between him and his brother – any competition?

“Nah. I’m thrilled for him. When you last saw us, he was writing away and I’m so glad it went so big for him. We watched Arsenal and Liverpool on Sunday. He’s doing good. We’re competitive, but we love each other.”

Given that his touchstones were the Clash and Scorsese, did he not think of writing rock songs or film scripts?

“Oh, I was too shy to be in a band and go on stage,” he says, grinning. “And I did write film scripts, but they were shit. I even wrote a radio play too, and it was shit. Plays were really my last option. The reason I didn’t write plays initially was because I thought theatre was the worst of all the art forms.”

The rest, as they say, is history. The reluctant young playwright sent the Leenane trilogy to various theatres in England and Ireland and, soon afterwards, he was contacted by Garry Hynes, who premiered The Beauty Queen of Leenane at the Druid theatre in Galway in February, 1996. It transferred to the Royal Court soon afterwards and opened to ecstatic reviews that set the tone for much of what was to follow. Having arrived, seemingly out of nowhere and fully formed as a writer, McDonagh soon found himself hailed as the most exciting new voice in British theatre and, at 27, was the first playwright since Shakespeare to have four plays performed simultaneously on the London stage.

Not a fan of the Queen, or hesitant producers: Martin McDonagh. Photograph: Antonio Olmos

Soon afterwards, New York too fell at his feet, with each of the Irish plays running in succession on Broadway to packed houses and equally effusive reviews, with one excitable critic calling him “the first great dramatist of the 21st century”. It was a tumultuous time in all sorts of ways for a young playwright who professed to hate the theatre and all it stood for, and whose success went hand-in-hand with a reputation for outspokenness and bad behaviour. At the 1996 Evening Standard theatre awards, where he had just been named the most promising newcomer, he and John refused to toast the Queen and McDonagh told Sean Connery to “fuck off” when the actor reproached him for his lack of respect. “It was drunken eejit stuff,” he told me in 2001, but the tabloids had a field day and his mortified mother refused to speak to him for a week.

In 2001, he made headlines again when he castigated the National Theatre’s Trevor Nunn for refusing to stage his new play, The Lieutenant of Inishmore, which mocked the pathology of Irish republican extremism in scenes that included a man having his toenails pulled out, several blindings, a corpse being chopped up and a cat being painted. According to McDonagh, Nunn was “big-headed” for thinking the production might threaten the then tentative process of the Northern Ireland peace process. Later that same year, he lambasted London’s “gutless and lily-livered” producers, who initially refused to stage his play, for fear that their theatres would be targeted by actual Irish terrorists.

Has his attitude towards the British – and Irish – theatrical establishment, and to theatre in general, changed in the interim? “Not really,” he says, without hesitation. “I guess I’ve accepted that theatre is never going to be edgy in the way I want it to be. It’s too expensive for a start. And, the audience seems to be complicit in the dullness. It’s like going to a fancy meal in a fancy restaurant with the attitude that, I’m here and I’ve paid the money so I’m going to enjoy it even though it tastes like shite.”

I take it he won’t be going to an Alan Ayckbourn play any time soon? “You know, I wouldn’t criticise him at all. It’s more the snobby, intellectual, political side of theatre that bugs me.” What about new younger dramatists like Polly Stenham? Does he not feel an affinity with her? “I haven’t seen her stuff. I met her at a party. She was pissed and nice.” He shrugs and sighs. “I know I should check out younger dramatists more, but, to be honest, I have no desire to go out and see a play. The whole nature of that experience just puts me off.”

What about someone like David Hare, I suggest – at least he’s actually writing political plays? He groans, slumps back in his chair and mimes putting a gun in his mouth and pulling the trigger.

For all that, McDonagh does seem more relaxed these days. Dare I ask, has he settled down yet?

“Ah now, Sean,” he grins. “I’ve got a lovely, girlfriend, Melina, we’re living together. We have a dog. But I’m not telling you what kind of dog [laughs].”

His writing voice, too, has shifted accordingly. “Hangmen is a play where he takes his time,” says Matthew Dunster. “There’s one scene that is 30 pages long – that’s about 40 minutes out of a 55-minute second half. To do that takes real confidence, and I think that confidence has come with age.”

When I ask McDonagh if success has also assuaged his youthful anger, he takes his time answering. “In a way, my next film is probably my angriest yet, but, yes, I do have a worry that the rage and the punk-rock joy of fucking with things isn’t there any more because of success and age. It even crosses my mind sometimes that I’m not raging any more because I’m almost part of theatre now – even though I don’t want to be.”

He pauses for a moment to collect his thoughts. “So, is the rage still there? I don’t know… It’s something I fight with myself about. Once you’ve had that anger and done your angry plays, it’s hard to go back there and do it all over again and, more to the point, it’s probably not good for the writing. The punk spirit is still in there somewhere, though – at least, I hope so.”

Hangmen opens on Friday at the Royal Court theatre, London and runs until 10 OctoberBox office: 020 7565 5000