Erne was the only son of Henry William Crichton, Viscount Crichton. His mother was Lady Mary Cavendish Grosvenor. On 31 October 1914, his father, a Major ("brevet" Lt. Colonel) in the Royal Horse Guards, was killed in action, aged 42, during the Great War. (He was awarded a DSO and a MVO, and is buried at Zantvoorde British Cemetery in Flanders.) Only a month later, aged seven, Erne succeeded his grandfather as the fifth Earl Erne. His mother later married Col. the Hon. Algernon Francis Stanley (a son of Frederick Stanley, 16th Earl of Derby), with whom she had one son and a daughter.