‘Good. There was more of a pattern in the conversation that time,” says director Max Stafford-Clark in his calm, gentle voice. In rehearsal is a scene from The Big Fellah, a new play by Richard Bean which is being produced by Max’s own Out of Joint theatre company.

The conversation itself has, however, been anything but calm or gentle. It takes place at gunpoint, and is riddled with expletives — not altogether surprisingly, for the play is about Irish Americans, and their relationship to the Troubles in Northern Ireland. When the rehearsal adjourned for lunch, I asked Richard what had made him choose that subject.

“I was in New York, I suppose six months after 9/11, and I went down to Ground Zero. I was very moved by the way that the whole of New York was in trauma at that time, and I felt that I really wanted to write about terrorism.

“I’d written one or two things about Islamist terrorism, but I thought it might be more productive to come at it from a different angle: in particular the way that we all support political violence when it’s in a just cause. The parameters of the argument are whether you consider something to be a just cause, or not.

“Most people would consider French resistance against the Nazis to be a just cause, for instance, but in one analysis it could be called terrorism.

“So I wanted to write in a broader way than just focusing on Islamic terrorism, and the obvious group walking about New York City six months after 9/11 were the 400,000 Irish Americans who live there.

“I thought to myself, ‘this is horrendous, what has happened here in New York, but you guys have been supporting Irish terrorism for 30 years’.

“And, of course, one thing 9/11 really did was to end financial support for the IRA overnight.”

Few, if any, directors have a longer or more distinguished record in nurturing new playwrights, and putting their work on the stage than Max Stafford-Clark.

I asked him what still excites him as he opens a new script.

“The great strength of English drama at the moment is the breadth of subjects that it takes on. I think theatre has learnt more from journalism in the last 15 years than from any other art form I’m aware of.

“Last night, for example, I went to the National and saw a play about climate change. The subsidised theatre in this country has given us a means to examine our own society, and to ask pertinent questions.”

Pertinent questions have been asked in many of Max Stafford-Clark’s productions, not least in The Permanent Way by David Hare, a searing indictment of mismanagement on Britain’s railways which culminated in a series of crashes, among them Ladbroke Grove, with its strong local resonances: after a performance at the Playhouse, I saw a girl sobbing uncontrollably in the foyer.

Can you intrude too deeply into an audience’s emotions, I asked Max?

“We normally expect laughter, that’s the most vocal response audiences are able to give. But I have occasionally stumbled across tears: that response is as valid and satisfactory as any other, because you’re dealing with emotion in rehearsal.

“For example, in the scene you just saw, Costello, played by Finbar Lynch, is obviously very upset because his daughter has died as the result of a heroin overdose.

“So as a director, I’m engaging the actor’s emotion in that.

“Indeed, at an earlier rehearsal, we talked of Finbar’s own son: tucking him up as a child, meeting him at the airport when he’d not seen him for three months, and how moving all that was.

“So you’re engaging the actor’s own emotions in the script, and engaging the audience’s emotions as well doesn’t seem to me to be invalid at all. It’s very much what you’re trying to do.”

Back in the rehearsal studio, Max is examining the characters’ motivation at each point in the story.

It is, Richard Bean pointed out, part of a long creative process.

“I originally wrote this play in Slovenia, typing away on a laptop and speaking Irish to myself. I was sitting in a room going, ‘I shat the horse’ — you type a line then see what it sounds like.

“In some ways I pay less attention to each character’s motivation to start with, then you come into rehearsals and you’re constantly analysing. Max’s process is very clinical on that.”

The Big Fellah premieres at the Newbury Corn Exchange between September 2 and 4, then comes to the Oxford Playhouse (October 19-23, tickets 01865 305305).