Do political plays have a sell-by date? Not when they are as dazzlingly intelligent, scrupulously well-researched and as funny and moving as this one by James Graham. The play has taken four years to make it from the National to the West End. It was originally written in response to the Conservative-Lib Dem coalition. The play takes us back to the Labour governments of 1974-79, which – first in a hung parliament then with the slenderest, fluctuating majority – faced a daily struggle for survival. Graham's stroke of genius is to set the piece in the engine rooms of Westminster: aka the offices of the Labour whips and their Tory counterparts as they wheel and deal to secure the votes of the “odds and sods”, the Liberals, Northern Irish, and Scottish Nationals.

Graham's play is richly alive to the grotesque comic absurdity of a situation so tight that sick and dying backbenchers have to be hauled in and dragged through the lobbies. There are occasions when this makes Lourdes look like Club Med. Ann Taylor (Lauren O'Neill), the sole female Labour whip, is surprised to be handed a screwdriver on her arrival for the purpose of “flushing” out members who may be otherwise engaged when the division bell sounds. The time-honoured convention of “pairing” absentees founders after the government side is thought to have cheated.

The author is still only in his early 30s and can already boast a string of astute and impressive pieces – from Eden's Empire, an early work about the Suez crisis, to the television play Coalition which focused, with great empathy and even-handedness, on the events that took place during those five frantic days in May 2010. One of Graham's great virtues is that he can be very funny, without ever stooping to easy cynicism. Not a widespread merit in works dealing with our political system. For all their rivalry, there's an almost chivalrous bond and a humorously grudging respect between the Labour deputy whip, Walter Harrison and his opposite number, Jack Weatherill, and this is beautifully brought out here in the rapport created by actors Steffan Rhodri and Nathaniel Parker. If the most admirably intransigent of the awkward squad is the dour, rather terrifying Audrey Wise (Sarah Woodward) who insists upon putting Socialist principles before party discipline and votes against proposed spending cuts, the noblest gesture we see in this play comes from a Tory.

Where the emphasis had previously seemed to fall on compromise and cooperation, you notice more this time round – post-Brexit, post-Trump – the signs that the post-war consensus is starting to crumble (Mrs Thatcher is waiting in the wings) and that Labour is about to collapse into factionalism. De-selected by constituency activists, Labour MP, Reg Prentice, crosses the floor. It's a foregone conclusion that Graham will write one of the most perceptive of the slew of Brexit plays that are now in the works. Watching This House, you can't help but ponder the paradox that our elected representatives are in danger of not getting a formal vote on Article 50 or any Brexit deal, for all the talk taking back and strengthening parliamentary democracy..