The Iraq war was fought for oil. Who says so? This time the charge is not levelled by the usual Bush/Blair haters but by Alan Greenspan, the lauded and cautious former chairman of the US Federal Reserve. Once famous for his gnomic economic statements, this time Greenspan is loud and clear. The former high priest of capitalism writes in his new memoirs: “I am saddened that it is politically inconvenient to acknowledge what everyone knows: the Iraq war is largely about oil.” Mr Greenspan’s pronouncement will cheer the anti-war left and confound his old friends in the Bush administration.

Yet surprise should be tempered. The US right is not monolithic. Its vitality stems from its variety. Many US conservatives opposed the war. Ironically, many so-called realists disliked fighting because it was not about oil alone - they were suspicious of democracy building and upsetting once-friendly local dictators. Still more US conservatives are isolationists who believe, like any British blimp, that abroad is bloody. Another tendency, to which Mr Greenspan leans, is libertarian which opposes big government - and war is the worst big government activity of all. Many free market economists, like their Marxist opponents, fall into the fallacy of believing that everything in politics hinges on financial self-interest. True, oil has always been an important factor in Middle Eastern strategy but even countries opposed to the war believed that Saddam Hussein had weapons of mass destruction. The real reason for the war was Saddam’s defiance and the projection of US power after 9/11.

Mr Greenspan has a more reasonable charge against the administration. Instead of cutting expenditure, it spent taxpayers’ money like a drunk who has won the lottery. Many American conservatives regard Bush as they once did Lyndon Johnson, who also broke the bank by paying for an expensive war in Vietnam while allowing domestic expenditure to rip. Prudent Mr Greenspan will almost certainly agree.