Chemist and mineralogist Harold Hartley was already involved in the use of chemical weapons during World War I; he was a member of the General Staff for Gas Operations. Until 1950, he acted as a senior scientific advisor to the government as a member of the Chemical War Council. His scientific work focused on the electrochemistry of non-water solutions and the self-crystallization of solutions and gas reactions, for which he was admitted to the Royal Society.
In 1930 Hartley moved into business. He took charge of the research department as vice president of the London, Midland and Scottish Railway. He also served as chairman of the British Rubber Producers Research Board, president of the Institute of Glass Enamels, and president of the British Gas Industry Society. After World War II, Hartley moved into the airline business. He became a director of European British Airways and then took over Britih Overseas Airways Corporation until 1949.