1918 On 3 January the Air Ministry was set up under a Secretary of State for Air advised by an Air Council. The Ministry's first task was to plan for the amalgamation of the Royal Flying Corps and the Royal Naval Air Service, which was effected on 1 April 1918 when the Royal Air Force came into existence.
1919 the Ministry became responsible for civil aviation
1920 the Ministry took over responsibility for aircraft production from the Ministry of Munitions
Between 1919 and 1922 the Air Ministry took over the Meteorological Office from the Treasury by stages; its own meteorological service and those of the other service departments was absorbed into the Met Office.
1921 Took on responsibility for the payment of service pensions, other than war pensions
1927 Took on the responsibility for research into atmospheric pollution.
1929 the Air Ministry took over control of the Observer Corps
1937 Following the Air Navigation Act 1936, certain regulatory functions concerning civil aviation were delegated to a newly-constituted Air Registration Board.
1940 responsibility for the design and production of aircraft passed to the Ministry of Aircraft Production, which also took over a number of Air Ministry research establishments progressively from that date.
Towards the end of the war the Air Ministry's responsibilities for civil aviation passed to a newly-created Ministry of Civil Aviation.
1959 On the disbandment of the Ministry of Supply responsibility for the supply of equipment to the Royal Air Force was returned to the Air Ministry, except for the production and supply of aircraft and supply powers relating to guided missiles, radar and other electronic apparatus.
1964: On 1 April the Air Ministry was absorbed into the unified Ministry of Defence.
Sources of Information
-  National Archives