The secret of this astonishing recovery is Labour's defining moral purpose. Labour is one of those institutions that appeal to people's hearts more than their heads. Others include the National Health Service and the United Nations. Britain's NHS may deliver poor care compared to other European health systems, but its faults are forgiven because of its powerful underlying commitment to provide the same medical care to every patient, regardless of income. The United Nations may have failed the people of Rwanda, Darfur and countless other wretched parts of the world, but its founding principles remain irresistible to idealists across the globe.

Labour isn't so much a political party as a moral project. Ask the average Tory what they believe and you'll get a variety of answers. Ask an average Labour member and they'll invariably say something like "social justice". For the Labour rank and file, theirs is the party of the poor, the unemployed, the weak and discriminated-against minorities. This self-righteous clarity is central to why, so soon after a terrible record of failure in government, the British people already tell pollsters that they "like" the Labour Party more than they like the Conservatives.

Neither Labour nor America's Democrats — who define themselves in similar ways to the British Left — will be defeated by conventional political weaponry alone. The contemporary Left is the political equivalent of the werewolf. Only a battery of silver bullets killed the mythical Beast of Gévaudan. Only a refutation of the Left's claims to moral superiority will cage its ambitions.

This great electoral challenge has increasingly motivated conservative politicians on both sides of the Atlantic — particularly since the end of the Cold War when political brands have been in a state of flux. Enlightened conservatives are unwilling to accept that the centre Right should forever face the handicap of being seen as morally inferior to the centre Left.