THE Diary’s editors were a credit to Georgian England’s social mobility. Surveyor and engineer Henry Beighton grew up on a farm; Thomas Simpson, a weaver, and Charles Hutton, son of a Tyneside miner, both taught mathematics at Woolwich military academy. All three were Fellows of the Royal Society.

Although male contributors were the comfortable majority, women asked and answered these brainteasers as equals; the Diary was specifically marketed ‘for the fair sex’, and founder John Tipper declared that “foreigners would be amaz’d” at his collection of some five hundred letters from women on technical subjects.

In an age when almanacks sprang up and withered almost overnight, the Diary lasted for 137 years, and at its peak reached 30,000 readers, by appealing explicitly to men and women for whom intellectual respect was a required foundation for friendship and love. “Wit join’d to Beauty” the cover for 1738 promised, “lead more Captive than the Conqu’ring Sword”. Or in Anthony Trollope’s words, “love desires an equal”.