For a playwright still only in his twenties, Nick Payne has had his fair share of success. After winning the George Devine Award in 2009, his first play to be professionally produced opened to a clutch of admiring reviews at the Bush Theatre, a debut that firmly established him as one to watch. He has been consistently producing well-received work ever since, including recent acclaimed sell-out hit Constellations at the Royal Court. The writer insists, however, that he has yet to feel the pressure of expectation that comes hand in hand with such achievements. “Maybe I should,” Payne laughs. But, as he goes on to explain, he feels that there is less pressure on him than there is on some other precocious talents. “Although I am quite young, there are playwrights whose first play has been professionally produced when they were much younger than me and who, in all honesty, have been more successful than me. In a way I’ve managed to creep around the outside and I’ve been deeply fortunate, but it’s not like I’ve written a smash hit and the success of it is terrifying.”

Payne’s route around the outside began at the University of York, where he “just read and read plays and screenplays”; an introduction to the dramatic form that inspired him to move to London after graduating in 2006 with aspirations of becoming a playwright. Other jobs and a series of stints in the Royal Court’s Young Writers’ Programme followed, until in early 2009 his play If There Is I Haven’t Found It Yet won the George Devine Award and was subsequently put on at the Bush Theatre. Looking back, Payne identifies this as a turning point: “The Bush had already said that they were interested in the play but they were a bit short on money to do it. Winning the award meant that they could get interest in it because it theoretically validated the quality of the play. It gave me a career, retrospectively, although at the time it didn’t quite feel like that because it didn’t happen immediately. I wish there was a clear chain of events, but there wasn’t really. In 2010, on the back of If There Is I Haven’t Found It Yet, I was the Pearson playwright in residence at the Bush, which was amazing. But I didn’t have a clear idea that this was the next thing I needed to do to progress my career – I still don’t, really.”

Early on in his writing career, Payne also took part in the Old Vic New Voices 24 Hour Plays, something he returned to three years later for the 24 Hour Plays Celebrity Gala. Talking about these experiences, Payne expresses a laid back approach to the challenge. “I don’t think it’s that scary, or at least it’s not that scary for the writers. I wouldn’t necessarily want to do it again, but it’s a very positive, supportive company of people doing it and a very positive audience. People want to enjoy themselves, and as long as you can write something that has a few good gags people will generally receive your play quite warmly. It’s also a chance to work with actors that I probably wouldn’t work with in any other scenario.”

Payne seems unafraid of challenges as a writer, an attitude which is reflected in the wide range of subject matter explored in his plays, from sex to quantum physics. “I tend to start with something I don’t know much about,” he explains. “There’s no real logic to how I might find something I fancy writing about, but once I have something there is a bit of a logic to how I might approach it, which is just to try and understand it. The most recent example is Constellations, which is not a play about physics, but the form is heavily informed by physics and cosmology, and I didn’t know anything about those things, so I spent a long time reading and speaking to people in an effort to understand them. It forces me to search for something outside what I might ordinarily choose to write about.”

Constellations centres around the relationship between a man and woman, played in the Royal Court’s recent production by Rafe Spall and Sally Hawkins, and how that relationship might have progressed differently under a series of varying circumstances. Inspired by ideas of chaos theory, Payne’s play explores the infinite possibilities of parallel universes, replaying the same scenes but with small differences that have a large impact on the ways in which the two characters interact. For Payne it was a significant departure from his previous work in terms of structure and one that was written with performance in mind. “There’s nothing wrong with a play posing challenges to a director or a creative team, but when why a play works particularly on stage has not been considered by the author it’s just a pain. So with Constellations there was a really conscious decision to write something that I hope could only work on stage.” Experimentation for experimentation’s sake, while having value in pushing creative boundaries, is not on the agenda for Payne. “For me, the form has to be tied to the content; unless there’s a tangible reason for experimenting, I don’t know why I would decide to do it. With Constellations, the reason was this extraordinary idea, and I felt that the form was a way of testing that idea and the ramifications of it.”

In contrast, Payne describes his current project as “the most linear thing I’ve written”. Lay Down Your Cross, a four-hander being directed by Clare Lizzimore at the Hampstead Theatre Downstairs, looks at the effect of bereavement on a family in the lead up to their son’s funeral. For Payne it is a welcome return to an idea he could not let go of. “Interestingly, it’s an old play,” he tells me. “I wrote it when I first moved to London – it was one of the first things I wrote. I couldn’t quite finish it, but every year since I’ve pulled it out and looked at it again.” Discussing the inspiration for the play, it is clear that this subject matter has captured Payne’s imagination. He explains that the idea was planted during a post-show discussion following a performance of Black Watch at the Edinburgh Festival. “There was a woman there called Rose Gentle, whose son had been killed by a roadside bomb in Iraq. I just found her an extraordinary woman. She was completely, understandably, palpably devastated by what had happened, and it manifested itself in a fierce, terrifying anger. It was heartbreaking.”

The continued fascination that has eventually resulted in the performance of Lay Down Your Cross reveals the thread that loosely connects all of Payne’s work, no matter how disparate the main plot and ideas. Like many playwrights, he is intrigued by relationships and particularly by families. “I suppose I’m interested in the dynamic of the family unit,” Payne reflects, “and the relationship of parents and children in particular. I don’t know that I could say why, necessarily; probably because I’m a child and I have a parent, and one day I might be a parent myself.”

It is this element of universality, combined with the specificity of the characters themselves, which unlocks what Payne believes to be the secret behind great drama: “We all have a dynamic that we share with someone else, whether that’s a close friendship or a parental relationship or a romantic one. The detail of those relationships is really fascinating on a person to person basis. In the best plays I’ve seen, that detail feels authentic but also very idiosyncratic.”

Lay Down Your Cross plays at the Hampstead Theatre Downstairs until 24 March. Tickets and more information available on the theatre’s website.