In the early 1900s, a visitor from Victoria, Texas, to Manhattan, New York, was relaxing at the racecourse when a waiter brought a bottle of wine to his table. It was sent with the compliments of W H Ellis. The Texan didn’t know who that was so asked the waiter to point out the benefactor. The waiter drew his attention to a dark-skinned gentleman sitting with his white wife – and he gave the shocked Texan a cheery wave. W H Ellis was a former slave from Victoria, masquerading as a Mexican and, that day at the races, claiming equal social status with someone who could easily have been a descendant of his previous owners. Only in America.

Karl Jacoby’s life of Ellis (1864–1923) is a study of the surprising flexibility of the Gilded Age colour bar. His subject was born light-skinned and close to the border with Mexico, which gave him a rare opportunity