“Tradition”. That was Ben Bernanke’s succinct reply recently when asked why central bankers continue to hold so much gold even while insisting that it is not money. Now, after a decade in which official gold reserves shrank continuously – outpacing growth in exchange traded funds nearly twofold – there may be a change in the air. Central banks made the largest purchases of gold in decades in the past quarter, says the World Gold Council.

Given the sums involved, Mr Bernanke could be forgiven for just shrugging. Even at near-record prices, the purchases, at about $8bn, amount to a rounding error in the scope of global reserves. Indeed, all the gold controlled by the US government, which has by far the world’s largest official reserves, equals just 3 per cent of America’s official debt, which just passed the $15,000bn mark. Even Italy, a particularly large holder of bullion (in third place globally with the 10th largest economy) would be able to retire less than 6 per cent of its enormous sovereign debt if it were to dump its 2,451 tonnes.

But while the dollar amounts may be paltry, Mr Bernanke must grasp that the symbolism is anything but. It is a mark of creeping distrust in the unofficial reserve currency, which nervous central bankers see being printed by the trillions even as America’s political leadership shows no sign of dealing with its daunting fiscal challenges. Fiscal worries are even more acute for the number two and three reserve currencies, the euro and the yen.