Why is there still no satisfactory life of Winston Churchill? That may seem an odd question to ask. Not only is there the official, eight-volume biography by Martin Gilbert, but scarcely a year passes without at least one new volume dealing with Churchill or his family. The latest, The Churchills by Mary Lovell, makes no attempt at serious history, but offers a potpourri of gossip about the family, from the Duke of Marlborough to the recently deceased young Winston, the great man's grandson.

Yet the more serious books also fail. Gilbert produced a chronology rather than a biography, smothering his hero in a mass of undifferentiated detail. Roy Jenkins was excellent on Churchill's period as a radical reformer at the Board of Trade after 1908, but insufficiently familiar with military matters to write effectively about the two world wars, and seems to have lost heart when he reached the 1950s - perhaps because he feared that Churchill, prophet of a supra­national Europe in opposition, had become a Eurosceptic in office.

Perhaps the most perceptive of the biographies was one by Robert Rhodes James, published in 1970. Provocatively entitled Churchill: a Study in Failure, it skilfully used the recently released cabinet papers to show why Churchill was so widely distrusted by his contemporaries. James's critical approach distressed the family, however, and prevented his appointment as official biographer.

There may now be too many biographies for there ever to be a good one. Perhaps, as Emerson thought, every hero becomes a bore at last. And yet, another factor may be at work. It could be that the man's career encapsulates facts about Britain and its place in Europe which we still hesitate to confront.

When Churchill became leader of the Conservative Party in 1940, he defined as his purpose "the maintenance of the enduring greatness of Britain and her empire and the historical continuity of our island life". He thought it important that we continue to rule India, Egypt and Sudan. Few in Britain today regret that we no longer do so. In an odd way, even Churchill recognised this. As he told his private secretary Anthony Montague Browne after he retired in 1955, "I could have defended the British empire against anyone except the British people."

Churchill was an imperialist because he saw the empire as a buttress of British power. Yet the central theme of his political career, which lasted from 1900 to 1955, was Britain's decline. Perhaps that was inevitable, but it was decline just the same. In 1900, Britain had been the leading power in the world, yet it was unable to win either world war without the help of the United States and Russia. After 1945, Britain found itself unable to contain Stalin without the aid of the US. By early 1955, as the Suez crisis 18 months later was to showed, Britain was no longer a world power.

So, judged by his own standard, Churchill had failed. And he knew it. He told his private secretary, "I have worked very hard all my life, and I have achieved a great deal - in the end to achieve nothing." It is absurd, however, to say now that he achieved "nothing". He may not have preserved British power, but he did preserve British independence. Only when the war cabinet papers were released was it appreciated by how narrow a margin Britain had survived in 1940.

In his war memoirs, he wrote: "Future generations may deem it noteworthy that the supreme question of whether we should fight on alone never found a place upon the war cabinet agenda - we were much too busy to waste time upon such unreal, academic issues."

But we now know that the war cabinet held five meetings during the crucial three days, 26-28 May, to discuss that very matter. Of the five members of that cabinet, Lord Halifax, the foreign secretary, favoured an approach to Mussolini and considered resigning in protest at Churchill's obstinacy, and Neville Chamberlain, the former prime minister, wavered but came down on Churchill's side. The two Labour members, Clement Attlee and Arthur Greenwood, supported Churchill.

Later, in June, there was a further attempt at compromise when R A Butler, then a junior minister at the Foreign Office, invited the Swedish ambassador to a meeting at which Halifax declared that British policy would be based on "common sense not bravado", a remark transmitted by the Swedes to the Italians as a British peace move. Churchill magnanimously dismissed it as a misunderstanding.

Churchill seems very remote from us today. His rhetoric appears to belong to an age long gone, his concerns remote from our own. And yet he remains at the heart of the debate about Europe, the question of whether Britain's relationship with the Continent is or is not a vital part of its being. That, perhaps, has been the main dividing line in politics since 1945, uniting as it does Churchill, Jenkins, Harold Macmillan and Tony Blair against Margaret Thatcher, Enoch Powell, Hugh Gaitskell and Michael Foot.

Churchill foresaw earlier than most the need for reconciliation after 1945. A united Europe was, in his view, the only way in which conflict between Germany and surrounding countries could be ended. Europe would become a common home within which previously warring neighbours could live together.

Today, it is often said, this old narrative is not relevant, and we need a new narrative. Perhaps that is right. The old narrative, however, is desperately relevant in the western Balkans.

In that part of our world, warring neighbours need a common home. Membership of the European Union seems the only way in which their ancient conflicts can be overcome.

Stability in the Balkans is of fundamental importance to Britain: they proved the tinderbox that set the whole of Europe alight in 1914. Indeed, twice in the 20th century, events in eastern Europe dragged isolationist governments in Britain into war. In 1938, confronted by Hitler's demands in relation to Czechoslovakia, Chamberlain announced that it was "a faraway country of which we know nothing". Douglas Hurd thought the same of Bosnia as foreign secretary in the 1990s. Churchill would never have made such a judgement.

He was not the prophet of the European Union, but, as a seeker of reconciliation, Churchill was a prophet of the unity of Europe and of a British connection with the Continent. He made many mistakes, more perhaps than most politicians, but he was right on the occasion when it mattered. And he was right because he saw that Europe was a civilisation whose values deserved protection. His Euro­scepticism in government in the 1950s, if that is a correct description, was a matter of circumstance and not principle. It cannot obscure the essential truth of Britain's relationship to the Continent, a truth that future British governments will have to confront as they struggle to achieve a more constructive engagement with the European Union. l

Vernon Bogdanor is research professor at King's College, London. His latest book is "The Coalition and the Constitution" (Hart, £20)