Arnold was born on 16 September 1920 in Hackney to Govshia Gersch (George) and Feiga (Fanny) nee Ogushevite. George worked as a dentist in his private practice and died in 1939. Arnold was a dentistry student and he also volunteered as a stretcher bearer in 1939.

Arnold enlisted at the beginning of 1940 and was at the start of his training in Torquay. Arnold was killed when he fell over the cliffs at Petitor, Torquay. His death certificate states that he was a cadet observer in the RAF and his cause of death was: ‘Fracture of base of skull caused by falling or slipping over a cliff there being insufficient evidence to show how such fall was occasioned.’