To an English theatregoer, not steeped in the politics and personalities of the Republic of Ireland, Sebastian Barry's new play Hinterland can be viewed simply as an everyday story of a former political leader now facing off the demons of his past. Here is a portrait of a man who was a bad father, an unfaithful husband and a corrupt politician; so far, so ordinary. What politician isn't flawed in one or more of these ways?

But in fact, the character is quite clearly based on the somewhat notorious figure of the former Irish President, Charles J Haughey. As a result, the man who plays him, Patrick Malahide, has remarked that when the play was seen recently at Dublin's Abbey Theatre, "We became a piece of news rather than a piece of theatre." And the Irish have long regarded the theatre as a forum that foments political dissent. When JM Synge's The Playboy of the Western World was premiered at the Abbey, it was famously greeted with riots. Malahide told a friend they were getting a very strong reaction there, and received a reply, "Until you hear small arms fire in the stalls, don't worry."

There's no such threat as Hinterland now crosses the water to the safe house of the National's Cottesloe Theatre. In fact, a far more urgent disruption is posed by the sound of snoring in the stalls. And Haughey, who has threatened to sue for defamation, might have a case if only for being reduced to such a dull, self-regarding character. In Malahide's monotonous, monochrome performance, there's little of the fire and fury that must have distinguished the man in his political career.

Irish critics, however, have pointed out that the actor bears an uncanny vocal resemblance to Haughey - Fintan O' Toole in the Irish Times comments, "Malahide almost entirely inhabits Haughey's voice. He captures quite astonishingly the way Haughey's speech mirrors the contradictions of his language, the ugly guttural tones riding on top of those rolling, stately, mesmeric cadences."

So much for the man and the method of the performance; what about the play? In this defiantly domestic portrait of the man, holed up in the handsome study of his Dublin mansion where he's attended by a loyal manservant, we find the politico protagonist troubled by a suicidally depressive adult son, a needy wife, and the arrival of a former mistress. But, while Hinterland is sometimes a quietly touching portrait of the devastation that one single-mindedly selfish man can cause others who come into his orbit, it only sparks into intermittent dramatic life.

The best scene occurs towards the play's end when the wife (the superb Dearbhla Molloy) faces off her rival, Connie (Anna Healy). This duel has the resonance of real life, rather than the remembered life that preoccupies the playwright and his leading character elsewhere. Here, Max Stafford-Clark's production, for his own company Out of Joint who have co-produced it with the National and the Abbey, finally finds some humanity and power behind the politics.

- Mark Shenton