At an age when most young Scotsmen were lifting skirts, ploughing furrows and spreading seed, Mungo Park was displaying his bare buttocks to al-haff Ali Ibn Fatoudi, Emir of Ludamar. The year was 1795. George III was dabbing the walls of Windsor Castle with his own spittle, the Notables were botching things in France, Goya was deaf, De Quincey a depraved preadolescent. George Bryan ‘Beau’ Brummell was smoothing down his first starched collar, young Ludwig van Beethoven, beetle-browed and twenty-four, was wowing them in Vienna with his Piano Concerto Number 2, and Ned Rise was drinking Strip-Me-Naked with Nan Punt and Sally Sebum at the Pig & Pox Tavern in Maiden Lane.

Ali was a Moor. He sat cross-legged on a damask pillow and scrutinized the pale puckered nates with the air of an epicure examining a fly in his vichyssoise. His voice was like sand. ‘Turn over,’ he said. Mungo was a Scotsman. He knelt on a reed mat, trousers around his knees, and glanced over his shoulder at Ali. He was looking for the Niger River. ‘Turn over,’ Ali repeated.

While the explorer was congenial and quick-to-please, his Arabic was somewhat sketchy. When he failed to respond a second time, Dassoud – Ali’s henchman and human jackal – stepped forward with a lash composed of the caudal appendages of a half dozen wildebeests. The tufted tails cut the air, beating on high like the wings of angels. The temperature outside Ali’s tent was 127° Fahrenheit. The tent was a warp-and-woof affair, constructed of thread spun from the hair of goats. Inside it was 112°. The lash fell. Mungo turned over.