In some ways the regulatory response that followed in the years after the collapse of Lehman Brothers has been a success. The days of racy balance sheets chasing outsized profits on wafer thin capital are largely over; replaced by a mantra of prudence and bread-and-butter lending to the real economy.

But one large part of the regulatory puzzle was never completed and that is worrying. Many of Europe’s banks are still susceptible to a fatal flaw that was exposed when the continent lurched into its own crisis.