The financial crisis has lent credibility to the notion of activist government. In the English-speaking economies in particular, the political culture of the past generation has stressed deregulation. In place of discretionary intervention, economic policy has aimed at establishing a framework of rules. The political beneficiaries of this change in economic climate have been parties of the Centre Left. The Centre Right has lost ideological ground; it lacks an obvious voice and commanding international statesman.

The Centre Left, by contrast with the Centre Right, has an opportune message and a clutch of would-be messengers. Policy in the US and UK is being driven by moderate social democratic Keynesianism. Gordon Brown remains far behind in the polls and beset by domestic difficulty, yet he appears a more substantial figure in public opinion in times of trouble. Spain has José Luis Rodríguez Zapatero. Brazil has President Lula da Silva. And then, of course, there is the progressive of the United States, the world's new communicator-in-chief, Barack Obama.

Conservatives internationally have struggled to accommodate the collapse of the Western financial system into their political narrative. John McCain, the unsuccessful Republican contender for the US presidency, adopted the populist message of blaming greedy bankers. For all his personal merits and the dignity with which he conceded the race, Mr McCain is a politician of yesterday, whose acknowledged lack of economic expertise hindered his campaign.

Republicans are now engaged in anguished, even bitter, debate about their electoral failure. It is symbolised in the appearance of Newt Gingrich as the principal speaker at the annual congressional Republican dinner to be held in June. Mr Gingrich replaces Sarah Palin, Mr McCain's running- mate last year. Both Mr Gingrich and Mrs Palin have strong bases of support within the party. But neither has popular appeal even in the US, where both are seen as polarising and doctrinaire conservatives.

The most high-profile conservative politicians internationally are thus those who occupy the highest elected office in important states: President Sarkozy of France, and Angela Merkel, the German Chancellor. But their respective constituencies are primarily domestic - in contrast to, say, the international recognition and influence of Margaret Thatcher in her political heyday.

Mr Sarkozy has allied with American concerns over Iran and made the important gesture of committing France to Nato's integrated military command. Yet he remains a distinctively national and even Gaullist figure. His conservatism is expressed in an aversion to the disruptions caused by market forces. He demands stringent - which is not the same thing as more effective - regulation on high finance. He envisages a new form of capitalism that “puts finance at the service of business and citizens”.

Meanwhile, Ms Merkel has welded a more successful coalition government than many expected. She is a quietly competent administrator, who marks a welcome contrast to the blustering anti-American demagoguery of her immediate predecessor, Gerhard Schröder. But she lacks political charisma.

The parties of the Centre Right thus lack a distinctive voice. David Cameron has marked out a position that fiscal stimulus is storing up future problems of debt and inflation. He has done much to dispel the impression that the Tories lack tolerance and an understanding of modern social mores. He has an opportunity to become much more than the British prime minister. There is a vacancy for a messenger with a coherent message for a global audience, waiting to govern from the Right.