Leonard was born 15 July 1914 in Hackney to Polish born Sidney (Sholem) and Kitty (Gitel) nee Isaacs and had a younger sister Gladys.

Leonard married Hilda Whetton in April 1939 in Hendon and later that year they are living at 3b Colin Parade, Hendon where Leonard worked as an office equipment representative and Hilda worked as a hairdresser. Leonard enlisted at Uxbridge in 1940 and worked as an aero engineer. On 14 June 1943 aged 29, Hilda died at Well House Hospital in Barnet.

Just fourteen months later Leonard died. His death certificate states that he died at 40 Parade Mansions, Hendon and his sister Muriel was with him when he passed away. The certificate states that his cause of death was: ‘1a Cerebral haemorrhage, 1b High blood pressure, 1c Chronic nephritis.’