Henry Izard was educated at Lancing College, and New College, Oxford. In 1914 he was selected for the post of Assistant District Commissioner in the East Africa Protectorate. When World War I broke out he was refused permission to join up in England, however in 1915 he resigned from his post and joined the Royal Flying Corps (later the Royal Air Force) and served with them in Tanganyika, Egypt, Persia and Mesopotamia. He returned to East Africa in 1919 as Assistant District Commissioner in Kenya Colony.

Izard was called to the Bar of the Inner Temple in 1929 and was promoted to District Commissioner in 1931. In 1936 he was seconded to Nairobi as Resident Magistrate and the following year was appointed Officer in Charge in Turkana Province and promoted to Senior District Commissioner. In 1938 he was seconded again, this time as Commissioner of Mines, and in 1939 was nominated as an Official Member of the Legislative Council.

On the outbreak of World War II Izard again wished to resign but was ordered to remain in Kenya to work on the Geological and Mineral Survey for minerals required for the war effort. He became a Member of the Nairobi Municipal Council in 1941 and in the same year was promoted to Provincial Commissioner. In 1944 Izard took up the temporary post of Public Relations Officer but retired from Government service the following February in order to become Executive Officer of the newly-formed Kenya Elector's Union.