According to a US congressional report, between 2009 and 2012, Apple funnelled some $30bn (£20bn) into an Irish subsidiary, without declaring any tax residence. This allowed the firm to earn $74bn in profits, paying little or no income tax to any national government. Apple had not just found a way to pay less tax, they had found the ultimate loophole: a way to pay virtually none at all.

Unfortunately, Apple's case is by no means unique. Today's multinationals are finding tax loopholes and bringing less and less cash into the public coffers of developed economies. So what is the problem? How can governments curtail this kind of tax behaviour?