Never So Good, National Theatre, London

There must be something in the water. First David Mamet declared himself through with being a "brain-dead liberal", and now Howard Brenton, the one-time self-professed Marxist and celebrated left-wing satirist, has written an elegiac and profoundly human portrait of the Conservative Prime Minister Harold Macmillan.

From the very first, genial, line, "I always had a lot of trouble with my teeth", Brenton shows us Macmillan the man. We see him first playing the Eton wall game, crushed by a domineering mother and an unfaithful wife (played with limp-wristed grace by Anna Chancellor) and fighting in the First World War, then his crowning as "Supermac", telling Britain it had "never had it so good" and his resignation in the seedy aftermath of Profumo. Brenton's Macmillan is a sympathetic mix of the ridiculous and the tragic, the J Alfred Prufrock of politics.

Howard Davies' direction is suitably epic, stylishly staging two world wars, the crumbling empire, the Suez crisis and the dawn of the swinging Sixties. The changing decades are rung in with dance – a spine-tingling waltz towards war, a jubilant victory lindy-hop, and a shimmy into the 1960s – and there are magnificent set pieces, including a moving Somme sequence.

As Macmillan, an unrecognisable Jeremy Irons perfectly captures a man who is fatally out of step with his time. His stuffy drawl through his soup-strainer moustache is spot on, as is his body language. He is well supported by Pip Carter as the youthful (but still absurdly old before his time) Macmillan, who dogs him mentally throughout his life. Ian McNeice's corpulent Churchill provides fine comic relief, while Robert Glenister's Boothby makes a horribly convincing journey from slick rake to bloated old duffer.

When asked by a journalist what causes the downfall of a government, Macmillan famously waffled, "Events, dear boy, events". Or, in today's political vernacular, "stuff happens". The beauty of Brenton's play lies in such modern parallels, the ever-repeating cycle of "events" at the chaotic epicentre of government: the sex scandals, the private Catholicism, the shady dealings of war, the "special relationship", the messy entrails of an economy in meltdown. And, at its heart, the less than charismatic man next door, seizing the reins of power from his glamorous predecessor after an agonising wait, only to see his premiership unravelling before his very eyes.

In rep to 24 May (020-7452 3000)