Considered too old to fly missions, Brooke-Popham served as a staff officer on the Western Front. Following the war, as a member of the RAF, he was posted to the Air Ministry and went on to command the RAF Staff College between 1921 and 1926. Promoted to air vice marshal in 1926, he served in various leadership positions in Britain and the Middle East until retiring in 1937 to become the governor of Kenya.
Brooke-Popham returned to active duty in September 1939 at the beginning of World War II. His first assignment was to help organize the British Empire Air Training Scheme in Canada and South Africa, a program that trained pilots from the British dominions. In October 1940, now an air chief marshal, he was appointed British commander in chief of the Far East, responsible for ground and air forces in the British possessions of Burma, Hong Kong, Malaya, and Singapore.
Plagued by organization difficulties, including the lack of a clear chain of command (area naval forces reported to a different commander), Brooke-Popham attempted to balance his military-diplomatic role and bolster British defenses against a possible Japanese attack. However, his ideas, including a proposed British invasion of Thailand, were mostly ignored. British and colonial troops under his command were ill prepared for the Japanese invasion of Malaya in early December 1941, and Brooke-Popham was relieved on 27 December. Many have assigned him the blame for the subsequent loss of Singapore. Brooke-Popham died at Halton, Buckinghamshire, England, on 20 October 1953.
Day, David. The Great Betrayal: Britain, Australia & the Onset of the Pacific War, 1939–1942. New York: W. W. Norton, 1988.; Falk, Stanley J. Seventy Days to Singapore. New York: G. P. Putnam, 1975.