The playwright, who has won countless awards, seen his plays staged on Broadway and turned into movies, has spent the last year and a half as the writer-in-residence at York Theatre Royal.

While in York he has been a powerful addition to Yorkshire theatre – to be expected of a playwright who Harold Pinter calls "a writer of blazing imagination, courage and insight".

"I'll be back in Yorkshire soon," says Freed, with a steeliness and commitment that those who have got to know Freed during his time in Yorkshire will recognise.

"The people, the place, everything has been wonderful here."

He then passionately adds: "I go away from York and Yorkshire, knowing that this is the beginning of a decade which will see this city and this county make its mark as one of the great theatrical centres of this land."

While in York, Freed has run masterclasses at the theatre and has encouraged the young generation of practitioners who are coming through. He has also worked closely with the university.

"At the moment, there are people in the city who understand what they have here, but in a few years' time, everyone will know it."

This is the way Freed talks – passionately, with a zeal and energy that belies the fact that he is in his seventh decade. It would be possible to dismiss it as PR-talk were it coming from anyone else. But Freed is, as they say in his homeland, the "real deal".

Not many other playwrights would see a production staged in a small studio theatre attract coverage from Vanity Fair. The production is Patient No 1, Freed's blistering attack on George W Bush. The political writer hoped to premiere the play in America, but when he began writing it, he thought the country was not ready for it. He sees York as anything other than a second choice.

"The potential for what can happen with the theatre here in York is truly tremendous," he says. The highly liberal Freed was the obvious choice to pen a piece about Bush.

"People kept saying to me, 'Write now about George Bush, before it's too late'.

"Then I would explain that to simply lampoon the moral idiocy of the man in the White House, while he was still in power, would only serve to create a false consciousness of superiority in the elite who attend such theatre in order to mock their bogey man in effigy, instead of facing him in reality. I could not do it.

"I lost sleep. I understood that to wait three years or more before speaking out was a scandal. Bile and loathing and terror may create any number of cabaret sketches. Yet terror alone without pity does not lead to catharsis. And how in all sanity could I, or any conscious American, pity the smirking, cheerleading, sadistic, lethal, little, jumped up, dry-drunk war criminal, who was destroying our country?" The answer was to write a play set in the future, when Bush was out of office and being cared for in a psychiatric clinic.

"Knowing this, I could start to write; to tell the story of how whole nations can go mad. Not only Nazi Germany or Stalinist Russia – but the United States of America. And that this was no laughing matter."

Patient No 1 is at York Theatre Royal to May 17.