'It's a deserted office that seems to be populated exclusively by theatre companies,' says Jack of his rehearsal space around the corner from Mansion House tube. 'I've just been working with Mydidae's two leads, the director and the stage manager. We've started our third week of rehearsals and it's going well. The actors - Phoebe Waller-Bridge and Keir Charles - are genuinely superb. It's an exciting time.'
Jack cuts an intense figure, eyes burning in a face that is both taut and animated. Energy comes off him in waves, an energy that lies behind his prolific writing output. With TV writing credits for the series Skins, Cast-Offs, This Is England 86 and This Is England 88 lending him a high profile, he has also written widely for radio and for film [The Scouting Book for Boys, 2009].
'Phoebe, who plays Marian, and Keir, who plays David, both have unique qualities. These actors fit these roles. The casting of them has been perfect. They've brought so much of themselves to it. It's a play that exposes the actors, literally and emotionally, so naturally they're a bit nervous.'
Mydidae, which means 'Mydas flies', is a modern day two-hander. 'The play is very personal and small. Its theme is essentially about mutual guilt between a married couple and how they deal with it. They're not in a happy place in their relationship. It's an intimate study of their lives.'
The play was commissioned by DryWrite, a new writing theatre company that challenges writers to work to specific briefs to engender argument, thereby engaging audiences. Jack says the locus of the play and the pared down cast is limiting, but this has only provoked in him a desire to improve his writing. 'This is DryWrite's first full-length production. My brief was simple. I was to write a play set exclusively in a bathroom. A normal domestic bathroom with a tub. That was the starting point.
'It took me four months to write the first draft. We're on draft four now.' Does he encourage input from the actors and director? 'Yeah, I take on board other people's comments. I listen to Vicky [Jones, the artistic director] and the cast. When you share your work and then incorporate the opinions of others, that's when things get good.'
But why write at all? 'I first started writing because I'm quite inarticulate, and I'd get home at the end of a day and rewrite the conversations I'd had. I'd improve them. When I first started writing plays, I felt I was a heroic person, but now through my work I feel I understand myself much more. When I'm upset, I write. It's cathartic. It helps me process situations. Writing is helpful in allowing me to get away from myself.'
Jack is comfortable across various mediums. 'Be it TV, film, radio or theatre, it works for me. I'm not precious about such things.'
He's a writer in demand, but does he know why? 'I don't know,' he grins, 'and I try not to think about it. But if pushed, I will say that I think I'm a truthful writer. A lot of television is about collaboration and I think I'm good at listening to other people and feeding off them.'
Is he a dramatist informed by the politics of the English class system like Edward Bond or Willy Russell? 'Not hugely, but class is a huge issue in this country, so it does tend to bleed into my work in some ways. Perhaps we're suddenly living in a more class conscious period. Though I am a member of the Labour Party, so I'm a political animal. The political world fascinates me and I aim to write about it more. It's one of my ambitions.'
When Shane Meadows, the director of the film This Is England [2006], planned to extend his tale through the TV series This Is England 86 and This Is England 88, he chose Jack to help him. 'Shane was looking for a co-writer for a TV series and he met and liked me. I was the first writer he'd worked with who wasn't a friend of his, but he is a friend now. He was looking for someone who was comfortable within the television format and Channel 4 thought I was a good fit for him. I'd call it the greatest experience of my working life. I remain very grateful to Shane. It was one of those projects where I felt totally in awe of the actors and director.
'Shane, from the original film through to each of the TV series, was telling the story of those people as accurately and as authentically as he could. I've been fascinated with the Woody (played by Joe Gilgun) character from the very beginning. It's a joy to write for Woody. The character has an unusual soul and spirit.'
When I ask Jack if he's worried about selling out, he gives his head a firm shake. 'I've not yet told a story I didn't need to tell. I remain ambitious about the stories I want to tell. Working with Shane has been invaluable with regards to this ethic, because his gut instinct is so strong about what's truthful and what is not.'
And the key to good writing? 'Well, for Shane, it's truthfulness. If something feels like it couldn't happen, then, dramatically, it shouldn't happen. Other writer-directors can tell fables, like Wes Anderson, for example. But with Shane, truth is all important.'
Jack is keen to collaborate. 'I'm currently writing a film for Joe Wright [Pride & Prejudice, Atonement] which I'm very excited about. However, it's not just about working with people who have proven track records, because I may meet someone who I think is so distinctive a voice that I feel I want to work with them. The director Adam Smith, who I worked with on Skins, is just such a person.'
By living in Luton, Jack enjoys a quieter life, his identity as a writer and denizen of London muted and perhaps altogether different. 'I'm open to writing about anything,' he says, 'but it has to be about something I can understand.
'I'm happy to be an original playwright and a gun for hire. There's always a danger that if you write your own stuff all the time, you will write the same story, so I require stimulation from great outside voices like Nick Hornby, who I've just worked with. You can get that juice, that inspiration, from working with other people.'
A perfectionist, Jack forever perceives imperfections in past work. 'I wish there was a button I could push to right the wrongs, but I don't consciously try to steer myself away from imperfections in my writing. I just write.' And with eyes still ablaze, he adds: 'I write best late at night, when my body is shutting down, but my brain is stilling itself, focusing. That's when my purest time comes.'
© Jason Holmes 2012 / jantholmes@yahoo.co.uk / @JasonAHolmes
Mydidae runs from 5-22 December 2012 at Soho Upstairs, Soho Theatre, 21 Dean Street, London W1.
For more information visit www.sohotheatre.com
Photographs courtesy of Chloé Nelkin Consulting. B&W rehearsal photograph by Lucy Patrick Ward