Harold Macmillan was the first prime minister I can properly remember, at least for the second half of his seven years in office. I can even remember myself, aged about fourteen, sniggering in the grammar school playground at jokes about Profumo and Christine Keeler. Howard Brenton, the author of this new play at the National's Lyttelton theatre, no doubt remembers him as well, but despite an excellent production by director Howard Davies and designer Vicki Mortimer, I can't see that he has managed to uncover any exciting insights into his protagonist's personal life or his political career. A biographical play about a real person is always a difficult exercise. Try to tell the whole story, and it becomes more narrative than drama. Concentrate on one or two key turning points, and the wider story of the life falls by the wayside. Brenton opts for the first variant, taking the classic approach of pairing the young Macmillan, played by Pip Carter, with the old Macmillan, played by Jeremy Irons. At the start, the old man watches while the young man dons his khaki uniform and goes off to fight in World War One, where he is wounded four times but survives where most of his contemporaries are killed. There are lots of loud bangs and explosions, but the writing is pedestrian. I was reminded of a bog-standard BBC drama-documentary. Then the play jumps forward twenty years to the late 1930s, skipping Macmillan's early career in politics and his marriage. The mature Macmillan takes over the action, while his khaki-clad younger self watches and occasionally interjects caustic remarks from the wings. But the device doesn't really pay dividends as it should, and for large parts of the second act Carter has nothing to do or say. Tom Stoppard used the same device with far greater imagination in The Invention of Love, which told the story of poet A.E. Housman through the contrasting figures of his older and younger selves, played by John Wood and Paul Rhys. Jeremy Irons is excellent as the older Macmillan, and so is Carter, but Brenton's writing lacks the subtlety of Stoppard's, and the central character -- cuckold, war hero, successful premier -- remains a mystery. Each decade in Macmillan's life is marked by a dance scene in a different style, a device which seems to me superfluous and in one case at least, misplaced After World War Two starts, the anti-appeasers led by Churchill no doubt felt vindicated enough to open a bottle or two of champagne, but to suggest that people began dancing in jubilation strikes the wrong note entirely. The dance music chosen for this scene seems more suited to 1944-45 than to 1939. The play's other main flaw is its predictability; it fails at every turn to avoid the bleedin' obvious. So we get Churchill drinking champagne at the Ritz, followed by Chamberlain waving a scrap of paper after seeing Hitler and announcing the start of World War Two into a BBC microphone. Macmillan's war service in North Africa is interrupted by a spectacular air crash, which brings a pyrotechnical but dramatically phoney climax to act one. In the second act the story revisits the Suez crisis at great length, with lots of clumsy expositional speeches, a few more bangs and explosions and President Dwight Eisenhower intervening to halt the Franco-British offensive by telephone. For some reason the U.S. president is wearing army uniform in this scene, which strikes me as a straightforward historical howler. By the time Macmillan becomes prime minister the play is nearly over, and what should be the climax is almost entirely devoid of interest. 'Supermac' the electoral wizard never comes to life, and his 'Wind of Change' speech in South Africa is treated very perfunctorily. Brenton's treatment of the strange triangular relationship between Macmillan, his wife Dorothy and Dorothy's lover Bob Boothby doesn't seem convincing either. After three hours, the play peters out more with a whimper than a bang. Brenton's a very experienced playwright, and delivers some snappy dialogue and some good one-liners, but there's a vital spark missing. Irons actually looks much more like Anthony Eden than Macmillan, and I think a play about the last prime minister before Tony Blair to lead us into a foreign military disaster would have made a much better drama. Eden is also more relevant to today's politics because he spent far too long as the deputy to a party leader who refused to step aside for him.