My husband complains that the disposition of teenagers in London is one of mocking hostility. I seem to suffer less from such encounters, and console him by saying it was ever thus.

In the 1790s ostlers’ boys would shout ‘Quoz!’ to disconcert an uncertain-looking passer-by. It was a word of doubtful meaning, perhaps connected with quiz.

A generation later, young loafers would call out ‘Oh, what a shocking bad hat!’ — enough to instil doubt in the most carefully dressed shopman or clerk. Neither men nor women were seen out in public without a hat.

The locus classicus for the phrase is in a book with a title perhaps more entertaining than its contents: Memoirs of Extraordinary Popular Delusions, and the Madness of Crowds (1841) by Charles Mackay (the natural father of Marie Corelli, the sensational novelist). Mackay gives a circumstantial origin for the phrase from a Southwark election, but I don’t find it convincing. It is quoted by Eric Partridge in his Dictionary of Catch Phrases (1977), though he is seldom credited with putting his finger on it.

The date of Mackay’s book is important because to the Duke of Wellington, on seeing the first Reformed Parliament in 1833, is attributed the remark ‘I never saw so many shocking bad hats in my life’. The account of this remark was not published until 1889, in Words on Wellington by Sir William Fraser, who had made a reputation back in the 1850s at the Carlton Club with his stories of Wellington. But he was only seven in 1833.

The disapproval is literally of the hats. The moral character of a bad hat is secondary. Shocking, used as a quasi-adverb like this, was thought a vulgarism (though Wellington wouldn’t have minded).

The Oxford English Dictionary contains no entry for shocking bad hat, but the phrase figures in its illustrations of other words. The earliest comes from 1831, when R. S. Surtees recounts the fortunes of Mr Jorrocks, in hunting raiment, reaching a spot opposite Somerset House in the Strand, to be met with boys heckling him with insults pronounced with the conventional Cockney V for W: ‘Vot a swell! Vot a shocking bad hat! Vot shocking bad breeches!’