A poster produced by the British government in World War II, with the text 'Keep Calm And Carry On' on a background of the flag of British Guiana, circa 1939. (Photo by SSPL/National Archives/Getty Images)

A poster produced by the British government in World War II, with the text 'Keep Calm And Carry On' on a background of the flag of British Guiana, circa 1939. (Photo by SSPL/National Archives/Getty Images)