Nevertheless, it was thanks to an English officer, Brig. Gen. Hugh Percy, that Mr. Richmond won his freedom, left America and gained some education in England, where he trained as a cabinet maker.

His first fights may have been provoked by racial taunts, but his sporting career began when he was employed by Thomas Pitt, the second Lord Camelford and Baron of Boconnoc — a boxing enthusiast and swashbuckling aristocrat whose turbulent life scandalized Georgian England before his death at 29 in a typically reckless duel.

Mr. Richmond not only began the brutal sport of bare-knuckle fighting at age 40, but also continued into his mid-50s, winning 17 contests and losing just twice. He mentored another freed slave, Tom Molineaux, and instructed the essayist William Hazlitt (and according to some accounts, Lord Byron) in sparring. So prominent was Mr. Richmond that he was among a group of pugilists invited to the coronation of George IV in 1821 to act as ushers.

Little is known about his English wife, Mary, except that she was white, or about their several children. But Mr. Williams argues that Mr. Richmond had straddled both race and class divisions of his time: his education and proximity to the wealthy made him more socially adept than many English-born boxers who rose from abject poverty.

To some, that only illustrates the limitations placed upon black people, some of which remain. “There has always been a route to black exceptionalism through sport,” said Kehinde Andrews, professor of Black Studies at Birmingham City University, who added that boxing success still reinforced some stereotypes attached to black people.

“Of course, it’s not bad that he was a celebrity,” said Professor Andrews, but his story tells us little about the mainly wretched conditions of a population of around 15,000 black people living in Britain in the late 18th century.