For much of the 20th century, the Conservative Party was one of the most formidable election-winning machines in Europe. The story of British democracy from 1918 to 1997 is one of Tory dominance punctuated by sporadic periods of Labour rule. Yet it is now 20 years since the party of Churchill and Thatcher last won a parliamentary majority. For a party whose raison d’être has often been the preservation of power, it is a melancholy truth.

The Conservatives’ misfortune is to be led by a man who failed to win the last election in the most propitious circumstances and who, after an energetic start, seems to have lost all sense of direction. As Jason Cowley writes in his review of an updated biography of the Prime Minister on page 42, the centre-right realignment promised by the coalition government has not happened. Rather than being rewarded, as they hoped, for their decision to enter government, the Liberal Democrats have been punished, nearly two-thirds of their 2010 voters defecting to other parties.

For a period, David Cam­eron, whose political views are an incoherent mixture of soft Thatcherism, shire Toryism and modish liberalism, sought to stand in the tradition of Disraeli and Macmillan as a One Nation Conservative, resurrecting the notion of noblesse oblige for an age of austerity. Vernon Bogdanor, Mr Cameron’s politics tutor at Oxford, says now of his former student: “He feels he has been fortunate; he has come from a fortunate background and feels he has a responsibility to look after those less fortunate than himself.” But Mr Cameron’s actions in government have defied this description. His party’s botched “reform” of the National Health Service (“the closest thing the English have to a religion”, in the words of the former Conservative chancellor Nigel Lawson) and his decision to remove the 50p income-tax rate have deprived Mr Cameron of any claim he had to be a One Nation Tory and have forced the abandonment of the slogan “We’re all in this together”.

Historically, one of the Conservative Party’s greatest strengths has been its ability to adapt pragmatically to change. It accepted the NHS, the welfare state, the Race Relations Act and, more recently, the minimum wage and devolution, even though it opposed them at the time. As Evelyn Waugh once complained, the Tory party has “never put the clock back by a single second”. Mr Cameron’s mistake was to betray this tradition through his chaotic reform of the NHS and his government’s error-strewn Budget. In his review of a new biography of Churchill on page 46, the former Conservative foreign secretary Douglas Hurd recalls Lord Salisbury’s advice that, since Conservative supporters largely accept the status quo, Tory ministers should “work at less speed and at a lower temperature than [their] opponents”. Would that Mr Cameron had done so.

The Conservatives are in retreat in those areas – the north, Wales and, definitively, in Scotland – that denied them a majority at the last election. Nearly seven years after Mr Cameron became its leader, the party has no councillors in Manchester, Liverpool, Newcastle and Sheffield. It is Labour alone that can now claim to be the true one-nation party: the party of the British nation.

Unable to win a majority by conventional means, the Conservatives have resorted to rigging the system in their favour through proposed changes to constituency boundaries and voter registration. Yet even these measures are likely to prove insufficient. If Mr Cameron is to win a majority in 2015, he will need to do what no prime minister has done since 1974 and increase his party’s share of the vote. To do that, he will have to decide whether he is a One Nation pragmatist or a consensus-breaking radical. At the moment, he is neither.