When I ask Charlotte Josephine how she began writing for the stage, she tells me her primary motivation was one of frustration. While auditioning for drama schools, she became increasingly dissatisfied with the lack of monologues available for women and decided to do something about it: “I used to write my own and say that someone else had written them. I’d go into an audition, nervous, and I’d get this little buzz when I’d say a fake name of a play. The panel would pretend to know who I was talking about, so I’d lie and say someone else had written it.”

This pugnacious and spirited drive manifests itself in Josephine’s debut play, Bitch Boxer; this one woman monologue, about a young boxer training for the Olympics, delivered a volley of knockout blows to audiences and critics when it bounded onto the stage more than a year ago. But as Josephine explains, those early forays into writing were crucial in exploring the kind of ‘voices’ so often lacking on stage and in the pages of anthologies: “I’d try and pick something really gutsy and strong, but I couldn’t find any contemporary monologues. So I wanted to write myself a really good part, as a woman, because I didn’t feel like I was getting them.”

Josephine began developing Bitch Boxer during a spell at the Soho Theatre Young Writers Lab. At the same time, she started training at the Islington Boxing Club and this was instrumental to the evolution of her writing, in allowing her to capture an atmosphere of authenticity: “I just wanted to know what it was like. To hit and be hit. It was so invaluable for the writing. The lingo and the language, the smells and the whole soundscape.”

Bitch Boxer went on to win the Soho Young Writers Award in 2012 and was produced as part of the Old Vic New Voices season in Edinburgh. Since then, the play has enjoyed success overseas, packing out the stalls down under when it performed at Australia’s Adelaide Fringe earlier this year. The furore of the Olympic games and the triumph of boxer Nicola Addams – who won the Gold Medal for Boxing – may have provided some context for the surge of interest the play received early on. Yet as Josephine explains, the play is about far more than boxing: “I don’t think I had realised quite how zeitgeisty and current it was going to be. I hadn’t realised it was going to be quite so popular as a theme. In lots of ways, it’s not really about boxing. It’s about someone’s struggle, the human heart and about fighting for what you want. It’s a really human story”.

For its debut production at the Soho Theatre, Josphine took on the role of Chloe herself. She continued to perform the role for the play’s national tour, garnering acclaim for her performance, as well as her writing. When it became apparent that the play would continue to tour, Josephine and Director Bryony Shanahan decided to audition new actresses for the role of Chloe: “Bryony was really keen to find the geekiness of Chloe. She’s very witty and self-deprecating, and we wanted to find that… As soon as Holly walked in, I was like, ‘that’s our girl!’. Because she had this natural clout that we really wanted to find.”

Holly Augustine had recently graduated from drama school when she auditioned for the role of Chloe: “I’d been warned that the first few jobs you get are going to be rubbish scripts. Then I was handed this beautiful 14-page gem of a job, and started training.” Augustine threw herself into the role with the determination and energy of a prize-fighting athlete, and as she explains, the physical dimension of the character was an essential element to tap into: “For me, it really came together when I started training properly and going to the club three times a week. Because the absolute core of steel it takes for someone to do that for a living – you can’t really put that into words.”

This muscular approach to inhabiting Chloe’s world meant undertaking an intensive, physical routine that recreated what it felt like to train as a boxer. The endurance, stamina and unbending discipline of an athlete – as they push themselves harder and further – underpinned Augustine’s preparation for the role. It was also a source of renewed energy and focus for every performance: “In a run, when you get to week three and you’re tired and your body hurts and for whatever reason you’re not feeling 100% raring to go – you have to find it in yourself. You have to dig deep.

In Chloe, we’re confronted by an unyielding resilience and fierce determination. Yet, as well as demonstrating physical and mental strength, she speaks to the audience with an expansive, emotional truthfulness. She is an athlete with tremendous heart, warmth and intelligence. As Augustine explains, this compassionate side is actually closer to reality then many might think: “Boxers are really nice. They’re a really chilled out breed and you don’t initially expect that because you’re used to seeing them so ferocious.”

On the other hand, there is never any sense with Chloe that she is waiting for a Romeo to turn up and save her. “It’s a female character that is strong, gutsy, competitive and aggressive in both the physical sense and in the ‘I wanna do something’ sense,” insists Josephine. When watching Bitch Boxer, it occurred to me that as a culture we seem perfectly comfortable with the idea of ‘gutsiness’ and ‘competiveness’ as aspects of male behaviour, but feel compelled to treat such traits as remarkable or unique when identified in women. In light of this, does Josephine consider Bitch Boxer to be a feminist play? “Those traits aren’t seen as ladylike in society. In order to be attractive I’m supposed to be passive, I’m supposed to look pretty and I’m supposed to be polite. Sorry, but I’m not going to be! It is bold and it is ballsy. So in that sense, it is a feminist play.”

Bitch Boxer is at Soho Theatre until 13 April. For more information and tickets, visit Soho Theatre’s website