Lyndon Johnson, the 36th US president, once said to his economic adviser, John Kenneth Galbraith: “Did it ever occur to you that making a speech on economics is just like pissing down your leg? It seems hot to you, but not to anybody else?”

Johnson might well have had central bankers in mind. Most of their speak feels hot to them and the small coterie of mostly financial sector economists who scrutinise central bankers’ every word and placement of punctuation marks. But the public has yet to feel the heat of the piss...