We speak the same language, stand united against terror, and are happy to pay a small coterie of businessmen millions to run our companies. The UK and US are, it would seem, the very best of friends.
In such a climate, Tamsin Oglesby's play, which promises to puncture any illusions of common ground with an acerbic dissection of one cross-Atlantic friendship, ought to feel particularly welcome.
The trouble is, the play never lives up to its billing, not least because Oglesby is far too busy churning out cliches to muster up anything that might pass for insight.
It takes only a brief glance at the character list - an American couple with a son, a British couple with a daughter - to envisage the entire dramatic arc of the play. Any remaining threat of unpredictability is annihilated by Oglesby's decision to start at the end: with the Yanks announcing to the Brits: "We don't want to be your friends any more."
Essentially what she deals in is caricatures: the American couple are forthright, organised and disingenuous; the English are bumbling, well-meaning and repressed.
The Americans speak in the language of therapists, take out adequate insurance and get things done; the English are creative (Martin is an inventor, Charlotte a linguist) but fail to live out their dreams.
Oglesby eventually digs below the surface, but the revelations - that Lori lacks a sense of belonging, that Martin can all too easily lapse into racism - merely feel as if they have been calculated to fit a set of themes.
There are glimmers of what could have been, particularly in a wonderfully modulated Thanksgiving dinner scene, during which Ed delivers a surprisingly sophisticated speech tracing the history of the "war against terror" back to Zarathustra. Listening to this, you wonder how Oglesby could allow her play to descend into a mindless barrage of patriotism and insults.
There are undoubtedly strong performances in Jennie Darnell's stolid, plodding production: Harriet Walter is taut with unexpressed neuroses as Lori; Hugh Bonneville is a breezy, blokey Martin; Siobhan Redmond's Charlotte is winningly scatty and occasionally fierce.
It is only Matthew Marsh, playing Ed, who has the opportunity to surprise with his character's unexpected complexity even as he limits himself to the dry, humourless, clipped stance we naturally expect of a rich American businessman.
Underneath it all, her point appears to be that the Americans and British are just the same: all descendants of the same folk, all equally obsessed with class. We never would have guessed.
· Until June 28. Box office: 020-7722 9301.
