There are many splendid prospects for a summer's Friday night. Cooping yourself up in the Barbican with ten actors playing Scottish soldiers who are having a hard time in Iraq is not the first one that comes to mind. But the National Theatre of Scotland's Black Watch has become a phenomenon. Since its run on the Edinburgh Festival Fringe two years ago, when it was performed at a drill hall near the castle, audiences have seen it in a Pitlochry hydroelectricity lab, under the Brooklyn Bridge and at an old factory in Sydney. At last, it has made it to London, to the Barbican's comparatively ordinary but, for this production, transformed theatre. The woman who sat next to me had queued for a return ticket since 3pm. I doubt she left disappointed: its acting and its staging are exemplary.
The piece - I hesitate to call it a play - follows a platoon from the Scottish Black Watch regiment as it moves in October 2004 from the relative sanity of Basra to Camp Dogwood, the triangle of death that the Americans had given up on. Impersonations of the Scottish Nationalist leader, Alex Salmond, and the then defence secretary, Geoff Hoon, slugging it out on Today remind us how controversial it was. To add insult to injury, the regiment, whose history dates back to the 18th century, is on the point of being merged. Against these odds, the lads display selfless bravery and we find ourselves liking them quite a bit. When three are blown up in an ambush, it is agony.
It is clear that the writer Gregory Burke, who spent two months in a pub in Fife interviewing former members of the regiment, intended his focus to be the mentality of the men, not the politics of the war. Two years on from its premiere, with Iraq fading from the news, the piece seemed heavily agitprop to me. At first the confused motives of the invasion are subtly suggested. A soldier is reading The Seven Pillars of Wisdom but does not know what T E Lawrence was doing in the desert because the front half of his paperback is missing.
Yet the idea that the west is in Iraq under false pretences becomes increasingly explicit. A grunt tells a television reporter that this is not defending your country, but invading someone else's. In the end the most thoughtful of the men, Cammy (terrific Paul Rattray), resigns in disgust and his commanding officer (plummy Jack Fortune) concedes that the regiment's 200-year-long golden thread has been "fucked up" by the "greatest western foreign policy disaster ever".
Burke seeks to disarm us at the start by throwing out the thought that theatre always portrays soldiers as pitiful creatures good for nothing but the army. Yet I am afraid this is exactly how I felt about them on the way out. He has a good ear. The jargon of war is fascinating and the men's badinage has its funny side, but Burke does not succeed in making individuals out of these soldiers, whose assumptions, speech and ambitions seem almost identical.
Indeed, this may be his point - that the army delivers a regimented and regimental identity to people whose education, class and income do not afford them anything more differentiated. If you dared write about homosexuals or black people in this way, you'd be in trouble.
I also found myself increasingly worried by Burke's structure, which features him nervously interviewing the alpha males in their Guinness pub. There are plenty of jokes about pooftah thesps and which nancy actor should play which soldier. This is self-deprecation: an artist pretending to cower behind his inferiority to real men and reality. But, of course, Burke does not consider himself inferior, nor does he think theatre inferior to life. As the evening wears on, he and the director, John Tiffany, deploy an armoury of theatrical weaponry. Two soldiers emerge magically from beneath the felt of a pool table, which is later used to represent their "wagon". An interlude of mime - largely incomprehensible, I might say - accompanies the opening of letters from home. The men killed in the explosion fall to the stage in slow motion from strings. The play ends in a frenzy of parade-ground exercises and battlefield mime.
This is a powerful finale to a major theatrical event, but its very theatricality is problematic. I concluded it was there to distract us from realising that the writer had not found anything very interesting about the boys themselves.
Pick of the week
Under the Blue Sky
Duke of York’s Theatre, London WC2
Catherine Tate in a "love among the whiteboards" comedy. From 15 July.
Where Soldiers Sleep
Landguard Fort, Felixstowe, Suffolk
This site-specific piece should be atmospheric at least.
Finborough Theatre, London SW10
Patrick Hamilton's Earls Court novel goes home for its stage adaptation.