Harold Warren Gill, an analytical chemist, was the son of Leonard Aldridge Gill and his wife Maud Warren Gill. He obtained the degree Bachelor of Science (BSc) at Kings College, University of London and became a Fellow of either the Institute of Chemistry (FIC). He came to South Africa in about 1913 to take up a position as lecturer in chemistry at the South African School of Mines and Technology in Johannesburg (forerunner of the University of the Witwatersrand), under Professor J.A. Wilkinson*. On the basis of his degree from the University of London, the University of the Cape of Good Hope admitted him to its BSc degree in 1914.
Gill published two papers around this time, "The recovery of iodine from residues" (The Analyst, 1913, Vol. 38, p. 409) and "The solubility of iodine in sodium iodide solutions" (Journal of the Chemical, Metallurgical and Mining Society of South Africa, 1913/4, Vol. 14, pp. 290-292). He became a member of the South African Association for the Advancement of Science in 1916.
By 1918 Gill had moved to British East Africa and was the chief residential chemist of the Magadi Soda Company, at Lake Magadi, south-east of Nairobi. He appears to have remained in Kenya for the rest of his life, later becoming a company director and consultant chemist in Nairobi. He was married to Mary Gill, with whom he had a son and two daughters.