The parliamentary press gallery in Westminster is often accused of treating their subject as though it were a football game: points are "scored" off ministers by their shadows, attacks are "lobbed back", you're a member of the "team". In Whipping It Up, which premiered last week at The Bush Theatre, writer Steve Thompson has gone further: this is politics as Machiavellian ping-pong played for laughs.

The scenario is a complicated but just believable one. It is late December, 2008. The Tories are in power, with a majority of just three. The setting is the hyper-realistically staged Whips' Office, which has reverted to what Maggie (Fiona Glascott), the formidable Labour Chief Whip who used to call this home, calls a "a public school dorm".

Traditional Tory voters were to be granted an early present - a bill to tax "tent poles" unashamedly aimed at the traveller community. It is designed to show them that the softie, "leftie" PM — no prizes for guessing who that is — is really one of them. But the scouts are upset, because they'll be hit by the tax too, and then, on the morning before the vote, a farmer shoots for no reason a couple of traveller children. Suddenly, it seems, the political mood has changed, and the government is in trouble on a bill it saw as a shoo-in.

Leading the charge to rally the troops is Alastair (with a powerful performance from Robert Bathurst), the deputy chief whip who throws terror into the hearts of young blue-blood backbenchers such as Guy (a suitably nose-in-the-air Nicholas Rowe). His metaphors are drawn not from football but from Sandhurst - he's a man who'd be right at home in the age of Kipling - the soldier MP must always be ready to lay down his life (or at least his career) for the party.

The jokes run thick and fast, but always along familiar lines. These denizens of the "Westminster village" regard their constituencies with contempt: Happiness, Alastair declares, "is the sight of one's constituency slowly disappearing in the rearview mirror." The description of David Cameron - the real-life Tory leader - mirrors many a grumpy rightwing editorial: "He's not 'proper' - he's just got an easy style. All that crap with the bike! We put him up front as a veneer. Plenty of old gargoyles in the Cabinet biding their time - hoping he would win the elections, then expose himself as a lightweight so that they could step in and take up the reins."