You show me yours and I’ll show you mine? Colleagues generally only swap salary details with co-workers furtively. One reason is that some employers discourage or even ban such discussions. Their stance is at odds with a trend for greater disclosure inspired by pay equality campaigns.

Finland provides one example. According to Reuters, a proposed law would force employers to disclose data on colleagues’ pay to workers who suspected gender discrimination.

That could help close Finland’s 16 per cent gender pay gap. But at a broader level, greater disclosure cannot guarantee everyone a raise. A recent working paper from the National Bureau of Economic Research concluded just this. Colleagues who share salary information end up earning less as a group, the researchers found.