In the criminally funny new play Cyprus Avenue, Belfast born playwright David Ireland tells some very hard truths about unionism, loyalism and republicanism though the prism of Greek tragedy.

If those truths hit home it's because he know's all about it, having grown up in their heartland in East Belfast.

From the bowler hats, swords and sash's to the all-male fraternities of the Orange Order, it's not too controversial to say loyalism is looking increasingly old-fashioned in the 21 century.

But you'd be foolish to take a bet against its determination to keep on marching. In Ireland's new play Cyprus Avenue the Belfast born playwright, 42, tackles the legacy of the Troubles and the inability of some within his own community to get past them.

What do unionists want? It's an increasingly complicated and fractured question, as time and history seem to be leaving that community and its centuries old rituals isolated or left behind.

Playwright Ireland, raised in the loyalist heartland of East Belfast, is asking the hard questions, but through the onstage character of Eric Miller (played with a slow burn intensity by Stephen Rea).

On the surface Eric seems to have it all. He has a family home in the most des res avenue in the city, he has and a wife and devoted daughter, from any standpoint he looks like a middle class success story.

But Eric is talking to a young psychologist. Something is going on. Then his lifelong prejudices and racism announce themselves almost from the moment he starts speaking. Why is he being psychoanalyzed, what on earth has he said or done?

It turns out that Eric thinks that his infant granddaughter looks too much like former Sinn Fein leader Gerry Adams. Soon he's convinced himself the child actually is Gerry Adams. What begins as an anxiety soon becomes an obsession. It's mad, and it only gets madder. Ireland goes to an extreme the better to understand the mindsets he grew up around.

“It's gone down much better than I thought it would,” he tells the Irish Voice, referring to the reviews and the audience reactions here in New York, where the show is currently playing to packed houses at The Public Theatre.

“I'm really surprised at how shocked the audience are by it, especially by the violence. There seems to be a real visceral reaction to the play. Lots of people love it and quite a few people hate it. The reaction seems to be much stronger than it was in London or Dublin or Belfast.”

So how did you arrive at Eric? What possessed you to create such an extreme character? “Eric, I hate to say this, but he's me. I think a lot of him is many of my fears about who I could have become. There's elements of my father in there and my grandfather. It's a weird thing to say because he's such a terrifying monstrous character.”

The idea for the play (an ordinary man sacrifices all he loves to protect his ideals) first presented itself just after he got married and started talking about having a family with his wife, he says.

“I got terrible fear about becoming a father, would I be able to meet the responsibility? And about the heritage I have, an Ulster Protestant heritage, of what that is and what I teach my children about what that is. The fears of that, of what you pass on to your children, my fear and neurosis, I took to the extreme and put it in my play.”

Eric makes it pretty clear that an embrace of the wider island of Ireland, and an embrace of an Irish identity, would lead to the dissolution of his identity. So he says no. “When I was commissioned by the Abbey, obviously that's the national threat re of Ireland. I was living in Belfast at the time and I had this sense of being commissioned as an Irish writer by the Irish theatre, but I don't feel particularly Irish, I don't have a strong sense of Irishness, I grew up in East Belfast, there were Union Jacks everywhere, and I had a real sense of being British.”

But like Eric in the play, when he arrived in England and Scotland (he now lives in Glasgow) he noticed that he was being embraced for his Irishness, being congratulated for it in fact.

“Girls liked me because I was Irish. But I didn't feel Irish. Then I thought, if I'm writing about protestants and loyalists and I'm being commissioned by the national theatre of Ireland – and my name is David Ireland – am I Irish? Am I British? What really am I? That tied in with the stuff about becoming a father. What do I tell my children who are growing up in Glasgow? Do they have an Irish father or a British father?”

After 30 years of war, where the IRA and Sinn Fein and Gerry Adams were considered the pole stars of evil by his community, it's not an easy question to answer for a unionist. “For me, had I not been interested in acting and theatre and all that I could very easily have joined the UVF. That option was open to me. I certainly had enough anger in me as a teenager. I was angry at the IRA and Gerry Adams. I had all those feelings within me but for some reason I was more interested in theatre than violence. Interestingly I have brought a lot of violence into theatre.”

In Belfast the play had a very different public reaction he says. “There was a lot of love toward it and a lot of anger and hatred. There were people who laughed and people who cried at the same things. At the end of the play, after he commits the terrible acts of violence he does, when he sits at the end and doesn't express any regret. He says in fact he could have done a lot worse. That's kind of where we're at in Belfast at the minute. We have been through all of this terrible violence and we haven't really had any sort of healing over it.”

Thankfully it's a society in relative peace, he adds. But the people who created these atrocities are a part of Northern Ireland's body politic now and there's so much mixed feeling about that. There's so much pain and anger on all sides that has not really been dealt with he says.

Eric would probably have voted for Brexit, wouldn't he? “Yes. But I don't have particularly strong opinions about it myself. For years growing growing up I was so passionate about Northern Ireland staying in the UK and the Scottish and English people around me couldn't understand why. Now that the UK is leaving the EU they're passionate about their countries leaving the union. People here now understand how these things can be important to people.”

Nobody talked about the effect Brexit would have on Ireland just as nobody talked about the effect that Scottish Independence would have on Northern Ireland, Ireland says.

“If that had happened, if Scotland had voted leave, that would have been tumultuous for protestants. I think we're living in interesting times. It's a good time to be a playwright. I feel like I got lucky with Cyprus Avenue. With everything that's going on in the world it feels like its resonating with people. I got lucky while the rest of the world got unlucky.”

For tickets to Cyprus Avenue call 212.967.7555.