Tate Britain

The three-metre tall painting of a man with a pearl-mounted sword sitting on a horse in elaborate regalia was bought by the Banque de France in the 1920s because it was believed to be a portrait of France’s Grand Dauphin, son of King Louis XIV, but was discovered to be that of a lord mayor of London, a work by John Closterman, and is now on display at the British capital's Tate Britain.