The Edinburgh Fringe Festival is a home from home for David Greig, so a natural place to catch up with the famous playwright. Having grown up in the city, he now lives in a village down the road, putting on a Fringe show every year since 1992, nurturing his prestigious talents from an early age.

“It’s still a huge privilege because you see the world’s best talent passing through. It’s an unbelievable window and a constant education, never without a challenge or stimulation. There’s always something that hasn’t been done before.”

That rather sums up David’s own work at the moment because while always prolific, the past year has been stratospheric — his plays appearing all over the world while simultaneously his new West End musical with Sam Mendes, Charlie And The Chocolate Factory, has become an overnight success.

Yet it’s in Oxford’s North Wall where his latest work The Event is being unveiled, written while waiting for Mendes to finish filming Bond, and Dunsinane is being revamped on the other side of town at The Playhouse.

“Don’t get me wrong, I’m very proud of Charlie but I try not to get carried away with the heady oxygen of the West End because it’s good for one’s ego and bad for one’s soul. So I saw it on opening night and then went home.”

David was brought up in Nigeria, but moved to Edinburgh aged 13. “If I’m from anywhere it’s Edinburgh. Some people have a sense that they grew up in a place, but I can’t say that, which means I have a confused relationship with my identification because at the same time I’m not quite Scottish either.

“But the interesting tension of who you are helps when you write. So it’s not a big deal but it does seems to make up part of one’s standing.”

It’s this conscious, questioning, all-seeing nature that has made David so successful, not that he was going to be anything other than a playwright, although in the early days in Edinburgh he trod the boards as well.

“One summer was like a mini festival and even though we couldn’t afford to rent a space, I acted, wrote scripts, directed and put on plays in a sub-let Masonic Lodge, and we slept seven or eight in my bedroom like sardines, and went on to win a Fringe awards with Stalinland.

“In fact, it’s being reshown this year as part of its 20th anniversary, which took me back, because it was great fun and a really enjoyable time in my life. That’s the thing about the festival — you can really try things out for the first time.”

So did he see it? “Yes, and I was worried it would be terrible. But instead I was just jealous of the freedom I had back then. It’s taken 15 years to get back to that comic lightness. I suppose I became a rather earnest young playwright, as young men tend to do.”

So how does it compare? “When writing The Event, which is dark, funny and compelling, I could feel the lure of that earnest young man,” he says. “So I’m glad I came to it now not 15 years ago. It’s about accepting the writer you are. You can spend a long time trying to be someone you’re not like Pinter, Beckett or Memet, rather than embracing the things audiences enjoy which you bring to the table. You learn to trust your own voice.” .

Instantly likeable, boyish and far more humble than he deserves to be, David, 44, makes a big effort to keep both feet firmly on the Scottish ground he so reveres. And yet taking on a project like Dunsinane, a sequel to one of the most famous plays in history, seems breathtakingly arrogant to an outsider. “I know,” he says in horror, “but I didn’t see it at the time. It hadn’t occurred to me.

“After seeing MacBeth in Dundee I realised I knew most of the places mentioned like Burnham Wood and Dunsinane, and that Shakespeare had never been there. So that great Scottish play was written by someone who wasn’t Scottish and hadn’t been to Scotland, yet he reduced the great King Macbeth. Now we know a lot more about him and have realised he was a good king, that interested me into writing a response.

“Plus the Iraq War had just started, which was very much a story of overthrowing a tyrant without preparing for the aftermath and the three things came together very simply. If you’d said it was a follow-up to MacBeth I’d have said ‘what, don’t be ridiculous’ but I realised too late what I’d done and it was terrifying and I nearly had a panic attack. All I could think was ‘what the hell do you think you’re doing’?”

“While you need a certain amount of emotional intelligence, I also have an inability to see how risky or arrogant I’m being — like walking the tightrope and not looking down — the bit that protects you from being an idiot and making a fool of yourself socially. You have to turn it off to write anything intelligent even though you might really screw up, even if it does bring you out in a prickling cold sweat.”

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