 Du Cane was born in 1901, the son of Charles Henry Copely Du Cane, of Braxted Park.His paternal grandfather Sir Charles Du Cane was a politician and colonial administrator; his paternal grandmother Georgiana was the daughter of John Copley, 1st Baron Lyndhurst.He joined the Royal Navy as a thirteen-year-old before resigning his commission as a Lieutenant-Commander in 1928.