Keith Barrett grew up in Melbourne where he attended Church of England Grammar School and later Ormond College, University of Melbourne. He graduated with a Bachelor of Agricultural Science and left for Queensland in 1914. When the First World War broke out he enlisted to become a private in the 2nd Field Ambulance, A. I. F. He fought in various places and eventually died of wounds received in fighting at Guemappe, France. His father later published his war diary which includes further biographical details.