Leslie was born in 1905 in Birmingham to Polish born Samuel and Esther nee Jacobs. Leslie married Fanny Silverman in Hackney in 1931.

Leslie died as a result of a traffic accident on the 28 November 1944. He was travelling in a lorry as a passenger between Uttoxeter and Tean. The lorry swerved to avoid hitting a bus conductor who crossed the road from behind the bus. Leslie fell against the door of the lorry which opened causing him to fall out and suffer serious injuries when he landed on the road. He died in London Road hospital in Stoke-on-Trent.