Paul Volcker, former head of the US Federal Reserve, was clearly exaggerating when he claimed that the ATM was the only useful financial innovation of the past 25 years. But he had a point. The service the financial industry provides to customers has not improved anything like as much as in other industries. And the efficiency of the industry itself has barely improved at all.

Meanwhile, many of the innovations that have emerged have proved disastrous. Think CDO-squareds or payment protection insurance.