The thing about the boy who cried wolf is that, in the end, he wasn’t joking. True, bankers have long said that they’ll quit London if beastly politicians don’t stop bullying them. And true, they’re emphatically still here. But the false alarms they’ve raised in the past do not in themselves rule out the possibility that London might be turning into a less attractive financial centre.

When politicians and regulators started applying the screws soon after the credit crunch, bankers issued their exodus threats loudly and defiantly. Now they do so privately and resignedly. They know that their collective bluff has been called and their credibility is severely diminished.