Where does the most British tax go missing these days? Perhaps in Panama, you think. Or Dubai. Or some tropical island where heartless rich people are drinking piña coladas served by starving local children.

Wrong. The most significant "tax gap" in 2013-14, calculated by Her Majesty's Revenues and Customs, was a £16.5 billion shortfall caused by small businesses not paying the taxes they owe. The equivalent shortfall for large businesses was £9.5 billion and £2.9 billion for individuals.

Glance at the headlines this week, though, and you might think all the world's wealthy are lying tax cheats. Never mind that most rich people don't have assets offshore. We've only seen a fraction of the stories from the 11.5 million documents leaked from the vaults of a Panamanian law firm, but the popular remedy is clear: hang the rich, shut down offshore financial centres, and, if you're an imperialist like Jeremy Corbyn, colonise them too.

So here's a truth that no politician will dare whisper: much offshore financial activity is legitimate and, in many cases, vital to the smooth operation of global business.