We are in the grip of the most significant global financial crisis for seven decades. As a result, the world has run out of creditworthy, large- scale, willing private borrowers. The alternative of relying on vast US fiscal deficits and expansion of central bank credit is a temporary – albeit necessary – expedient. But it will not deliver a durable return to growth. Fundamental changes are needed.

Already it must be clear even to the most obtuse and complacent that this crisis matches the most serious to have affected advanced countries in the postwar era. In a recent update of a seminal paper, released a year ago, Carmen Reinhart of Maryland University and Kenneth Rogoff of Harvard spell out what this means.* They note the similarities among big financial crises in advanced and emerging countries and, by combining a number of severe cases, reach disturbing conclusions.

Banking crises are protracted, they note, with output declining, on average, for two years. Asset market collapses are deep, with real house prices falling, again on average, by 35 per cent over six years and equity prices declining by 55 per cent over 3? years. The rate of unemployment rises, on average, by 7 percentage points over four years, while output falls by 9 per cent.