Michael Bloomberg has some skin in the Britain game: his ex-wife is British, his daughters have our passports. So he was saying it as a friend when he commented this week that he thought Brexit was “the single stupidest thing any country has ever done” (aside from electing Donald Trump, he added, of course).

True, it is hard for Bloomberg to imagine why people might vote against a system that worked perfectly well for billionaire captains of industry. And whatever follows may knock a few points off the GDP. But is it really the stupidest thing any country has ever done? Here is some Bloomberg News for Mike: the competition is stiffer than he thinks.

The Trojan horse

“What’s that?” “A giant wooden horse the Greeks inexplicably left after a 10-year siege.” “Right. Shall we run it through the X-Ray machine before we drag it in?” “Nah.”

King Vortigern’s mercenaries

King Vortigern, fifth century ruler of the Britons, had a problem. Pictish invaders were up to their usual invading tricks. He needed an easy way to repel them. Solution? Saxon mercenaries. Lots of them. But it turned out that cheap foreign labour has its issues: seeing the glories of England, they sent for their friends, and took over Vortigern’s country.

Myanmar’s nines crisis

Stalinesque Burmese president Ne Win had a favourite number. Don’t we all? He was a bit more serious about his. In 1987, he abolished at a stroke all bank notes that weren’t divisible by it. This left only the 45 and 90 kyat notes in circulation. That’s right, mathematicians: his favourite number was nine. In this inverse monetary bingo, anyone whose life savings were differently denominated was instantly bankrupted. National chaos ensued, and the national resistance movement headed by Aung San Suu Kyi was born.

Facebook Twitter Pinterest The Henry Frank a Mississippi steamship, laden with cotton. Photograph: Bettmann/Bettmann Archive

The Confederacy’s cotton ban

At the outset, the south was widely predicted to win the US civil war. These, after all, were the heartlands of a still overwhelmingly agrarian economy. Perhaps unsurprisingly for a people who had pegged their historical mantle on the right to keep slaves, the south then chose to enact another colossal face-punch. Attempting to force diplomatic recognition from the European powers, they placed a ban on the export of their No 1 crop, cotton. Their already faltering economy shrank like a cashmere jumper in a hot wash.

The Maginot line

“Let’s spend half our defence budget on a country-long line of state-of-the-art interlocking fortifications on the German border.” “Right. But do you think they’ll come through Belgium?” “They won’t.” “You said that last time.” “Exactly. So why would they do the same thing again?” “Fair point.”