Weak productivity growth has puzzled economists and policymakers but it doesn’t seem to have hurt investors: the period 2009-2016 might even be called “the Goldilocks Slump”. Ample slack in job markets ensured little bargaining power for workers, whilst central banks battled deflationary impulses with a combination of low (or negative) rates and asset purchases. The net effect has been falling real yields and tight risk premiums.

But productivity growth does matter. And we are nearing the point where its absence will be of overwhelming importance to financial market investors.

The economic expansions that have occurred in the United States and the United Kingdom over the past five years have been explained almost entirely by peopleworking more, not smarter. Explaining this weakness in labour productivity with a high degree of confidence has so far defeated careful enquiry.