The word ‘hoax’ did not catch on till the early 19th century. Before that one spoke of a hum, a frump, a prat or a bilk. But 18th-century Britain, even if not rife with talk of ‘hoaxes’, was full of incautious souls at risk of being bilked. James Graham, a Scottish quack, was able to charge infertile couples £50 a night to lounge in his Celestial Bed, which had a mattress lined with hair from stallions’ tails. The artist Ann Jemima Provis and her father, Thomas, caused embarrassment to the Royal Academy by conning its president, Benjamin West, into thinking they had stumbled on a rare manuscript that would allow him to emulate the luminous style of the Venetian masters. William Charlton painted black spots on the wings of a yellow butterfly and announced thathe had discovered a new species, which in due course found its way into the British Museum.