The audience is noticeably quiet as it shuffles out from Giles Havergal's production of Observe the Sons of Ulster Marching Towards the Somme, Frank McGuinness's tremendous, difficult 1985 play. There have been (uneasy) laughs during the evening, but a complex and unusual gloom hangs over the theatre when it ends.
It's hardly surprising. McGuinness doesn't offer an easy night's entertainment, nor does his play answer its vexed questions about religious belief, loyalism, masculinity and war. It also ends with an abruptness that seems deliberately to leave its audience in the same existential limbo as the eight Protestant soldiers heading towards almost certain death at the battle of the Somme. Since its first production, the play has always been refracted through the local and political context (not least the health or otherwise of the peace process in Northern Ireland) in which it is performed. So it is in Glasgow, a city still shaped and scarred by sectarianism.
The play is as difficult to perform as it is to watch: McGuinness's writing has a poetic, dreamlike quality, and he overlaps two time realms. Pyper (Stephen Cavanagh), the play's anti-hero, is the only soldier to survive, and his elderly self appears on stage as the younger men meet, bond, tussle and face their fate. Cavanagh and Brian Ferguson, as Pyper's lover, David Craig, capture just the right grim tenderness between the men. Kenny Miller's claustrophobic set is equally impressive: at the back of the stage is a steep slope formed from what looks like a bank of guns, which transforms into a river bank, then the side of the trench.
"Answer me why we did it," says one of the soldiers. This question - why these men volunteered, who or what they were fighting for, why Irish nationalism has neglected to address such sacrifices within loyalism - scorches through the drama. For British audiences, watching through the tangle of Anglo-Irish relations, and especially in the shadow of September 11, with its new twist on the relationship between faith and war, the play brings many more answer me whys, an almost unbearable weight of them.
· Until February 23. Box office: 0141-429 0022.
