In the UK, a female cabinet member has been criticised for retelling a joke originated by a female European Union Commissioner, who in turn appears to have heard the joke from a moderator at the World Economic Forum in Davos. The joke goes something like this: “If Lehman Brothers had been Lehman Sisters, there might not have been as much turmoil in the markets.”

Is there any truth in the idea that companies with more women directors on their boards do better than those without? Is oestrogen the performance-enhancing drug that can wake up sluggish boards, improve the quality of earnings, and hold testosterone-driven risk-taking at bay?