Chevalier is a biopic of Joseph Bologne, Chevalier de Saint-Georges, whom you’ve probably never heard of, as I hadn’t. He was an 18th-century French-African virtuoso violinist and composer who wowed everyone in his day – in 1779, John Adams, then the American ambassador to France, called him ‘the most accomplished Man in Europe’ – but was erased from history and is only lately being rediscovered.