It was George Bernard Shaw who said "England and America are two countries divided by a common language", and lyricist Ira Gershwin who once wittily catalogued the linguistic differences - "You say eether and I say eyether/You say neether and I say nyther;/Eether, eyether, neether, nyther -/Let's call the whole thing off!"

Now, in a new play called US and THEM, playwright Tamsin Oglesby has lengthily dramatised the story of two 40-something couples from either side of the Atlantic who at the start of the play decide to follow Gershwin's advice and call the whole thing off. It then rewinds from that moment to chart how they fell in with each other after a chance meeting in a New York restaurant, and how they eventually fall out in a mire of missed business opportunities and an apparently shared family tree that's supposed to connect them turns out to make them not as close as they think they are.

Oglesby's overwritten play - it runs to 19 scenes in two acts - often wittily but sometimes too obviously observes the cultural and philosophical mismatches between them, from the way to deal with verrucas and problems in restaurants, to the bigger differences that ultimately tear them apart as mutual incomprehension about what's important simmers into outright contempt.

Ogsleby marshals a wonderfully antagonistic penultimate scene that fiercely provides arguments for both sides, though an inevitably partisan British audience showed its true colours when it applauded lines against the Americans. At a time when our respective leaders are fond of citing the 'special relationship' that exists between our two nations, this play provides a contemporary riposte that is full delicious insults. As the American Ed tells the British Martin, "Don't talk to me about laws and systems with your highest crime rate in Europe and your collapsing infrastructure and your rude, incompetent, ugly people and your arse-licking prime minister… You can't even run your own country. You have a Scotsman in charge, you get an American to fix your Underground, a Swede to manage your soccer team…."

But then Martin replies, "At least we have society. Your country is held together by nothing but a whining ego. And at least we elected our arse-licking prime minister. Our country is run by its democratically elected representatives. Not some illiterate trigger-happy ex-alcoholic who can barely speak English…. And licking arse is better than kicking it."

The scene, though brilliantly executed, is a long time coming. And if the writing that precedes it is sometimes derivative, the staging is even more so. You don't need to know that director Jennie Darnell was associate director for Yasmina Reza's Art and Life x 3 to spot the staging similarities to Matthew Warchus' productions of those plays, with jangly electronic music punctuating the scenes changes and fluorescent light frames around the proscenium.

But Darnell is at least beautifully served by her strong cast that includes Hugh Bonneville and the wonderful Siobhan Redmond as the English couple and Matthew Marsh and Harriet Walter as the Americans, with Jemima Rooper and Jonah Y Lotan as their respective kids who find their own way to each other even as they are cutting themselves off from their parents.

- Mark Shenton