Born in Forbes, New South Wales, on 27 February 1903, Lester Brain was the second son of an English mining engineer and manager, Austin Brain, and his Australian wife, Katie.
Nascido a 27 de fevereiro de 1903 em Forbes, Nova Gales do Sul, Lester Brain era o segundo filho de um engenheiro e gestor de minas, Austin Brain, e da sua esposa australiana, Katie.