As the world’s central bankers gather in Jackson Hole, Wyoming, for their annual retreat, it would be no surprise if they opt for a quiet walk in the beautiful Grand Teton National Park during breaks in the programme, rather than the white-water rafting that is also on offer.

The crisis that has engulfed global financial markets is two years old and next month is the anniversary of the uncontrolled failure of Lehman Brothers that led to a “sudden stop” in the global economy and the deepest post-war recession. For policymakers, it has been a white-knuckle ride.

The mood should be a bit better than last year’s meeting. The disorderly collapse of Lehman Brothers helped to turn a global financial crisis into a global recession. The efforts of governments...