We would not have monetary policy committees: we’d have a computer in a protected vault, moving interest rates around according to a rule like that proposed by John Taylor. Unfortunately, we have not got there yet, so the demand for real economist people persists.

But although macroeconomic failures show that our subject is hard, I think we have made lots of progress.

Compare the Great Depression to the financial crisis. In the US, output fell by 30pc to its trough. Following 2008, it fell by 4pc. A lot of factors are at work here. But part of it was about lessons we have learnt in macroeconomics.

For example, we understand better why a fiscal stimulus works and when it’s beneficial. The support for this in the economics community helped bring about the US fiscal stimulus package of 2009.

Also, we have learnt about monetary policy. We have learnt that money works without its value being pinned to the value of gold. Insights gained by trial and error over this “century of failure” freed central banks this time around to cut rates vigorously and go further, when they hit the floor to interest rates, and do quantitative easing. The great US economists, Friedman and Schwartz, and later, former Federal Reserve chairman Bernanke, concluded that the Fed was complicit in the scale of the Great Depression. Future historians will observe that even if modern central banks were not perfect, the recession following 2008 would have been worse without them.