Universal Man: The Seven Lives of John Maynard Keynes by Richard Davenport-Hines, book review: Economist was every inch a liberal

Who said economists were dull? For anyone practising economics today (declaration of interest, that includes me) this book is a treat. We can only dream of being as influential as Keynes was in his day. He shaped economic theory. He used knowledge to influence policy and change the course of history – as he did most emphatically in the first half of the 20th century by shaping global economic architecture.

We read endlessly about Keynes the economist. But he was so much more and this unputdownable book explores not so much Keynes the economist as much as Keynes the man. The ''dismal science'', as Thomas Carlyle called it, is thought to breed boring nerds. This book shows this to be a monumental error of casting. Keynes was what Richard Davenport-Hines describes as a ''Universal man''. He was variously a loyal civil servant, a supporter and lover of the arts, an internationalist, a businessman, and a shrewd investor in art for the nation, to name but a few.

Not all was perfect. Keynes had all the unpleasant elitist and anti-Jewish prejudices of his class and generation. And what to make of his voracious homosexuality, which was a large part of his life? He was part of the Bloomsbury set in London, where sexual encounters among the same sexes was frequent and from where many of his lovers came. He travelled far and wide to satisfy his sexual appetites. In the end he found love and happiness in his forties, getting married in 1925 (with his former lover Duncan Grant as his best man) to Lydia Lopokova, a Russian ballerina in whose arms he died of a heart attack in his early sixties, exhausted by trying to negotiate with obdurate Americans whose politicians disliked British imperialists and upper-class Liberals, which Keynes was, in equal measure.

Keynes was exceptionally bright, getting through tough competitions into Eton in 1897, where he was a King's scholar, into King's College at Cambridge in 1902, and into the civil service in 1906. He read avidly and quickly – this was a trait he thought was extremely useful. He devoured newspapers and periodicals and claimed that newspaper reading taught him how to skip, arguing that ''every serious reader must have this art''.

He railed against stupid decisions, usually those of politicians. He often blamed falls in output and rises in unemployment to ''administrative obfuscation'' and deplored decisions taken without full information. An early evidence-based propagandist, he was frustrated when negotiations were based on imprecise and disorganised data. Nowhere was this more evident, and hence to him unjust, as in the post-Second World War debt negotiations with the US, in which he took part facing a new world power which seemed to care little about giving the country that beat the Nazis any financial leeway. In between the wars, he had already come to the conclusion that ''the future of the world lies with America''.

He changed his views , even strongly held ones, if the evidence suggested otherwise, and he was an avid listener and debater in the many private dining and discussion clubs he had either started or joined. He was prepared to experiment to get results. And yet he had only had eight weeks' training in economics, having been taught by Alfred Marshall, his father's early mentor who encouraged the young Keynes to specialise in money and banking. But he loved it.

In his first spell as a civil servant he found work in the Indian Office and then the Treasury boring. He resigned in 1908 to become a lecturer at King's, Cambridge. Back in the Treasury, during the First World War, he despised the politicians who couldn't resist the pressure put on them by a popular press to institute conscription. He longed for a working-class revolution that would defeat the Military Service Act as he did not ''see the intellectuals do anything but ply a feeble pen occasionally and feel miserable''. Working at the Treasury in 1916 won Keynes a certificate of exemption from military service but he still applied for separate exemption as a conscientious objector. Characteristically, he didn't bother to turn up to his tribunal because he was ''too busy'', but somehow was issued with an exemption again later that year, which this time he did not contest. He advised his ex-boyfriends Duncan Grant and David ''Bunny'' Garnett to get into agriculture to avoid being sent to the war themselves. He never worried about expressing opinions. In 1938, when he was chair of the New Statesman, he deflected criticism of the magazine's Lonely Hearts style advertisements which ran along the lines of ''man not interested in the fair sex seeks...''

And, of course, he liked sleeping with men. He had no qualms about himself and his male friends all falling in love with each other, although the shadow cast by Oscar Wilde's imprisonment in 1895 encouraged Keynes and many of his like- minded contemporaries (there were many) to compartmentalise their private and public lives and be as secretive as possible. Much has been written about his activities and the book relishes going into details of who was sleeping with whom, who was enjoying a ménage à trois and how many of the men in later life, who worked alongside Keynes in public life, had been his ex-lovers.

Like any human being he had his pet hates. He detested nail-biting. He would quote Aristotle who he said had believed that "biting of one's fingernails is bestiality along with buggering bulls and ripping open females with a view to devouring the foetus"! He said to his wife after seeing one candidate for entry at King's in 1935, who had seemed to be "much the cleverest on paper", that "he is excellent – there cannot be a shadow of a doubt about it. Fingernails as long as yours...Turing his name..."

He wasn't always right. During one of his more depressed periods in 1919, Virginia Woolf noted Keynes' remarks to her that "Eton is doomed; the governing classes, perhaps Cambridge too."

Well they are all still there. And the bits of his personal life that Davenport-Hines focuses on probably show him in a much more flattering light than the real man. But in the field of economics Keynes' impact is immense. It is only a small exaggeration to say he single-handedly invented macroeconomics. His insights on the stability of capitalism and its implications for the role of government will long outlast the fiercely contested details of the neo-classical rehabilitation that led to the political rejection of Keynes by Margaret Thatcher and Ronald Reagan. Keynes was a life-long Liberal whose mission as an economist was not only to save capitalism from communism but also to save it from itself. And it is for that that we can forgive Davenport-Hines' rather too flattering view of him as a human being.

Vicky Pryce's new book, 'It's the Economy, Stupid', (Biteback, £15.99) is out now