In September 1939, the British Army was in process of expanding their anti-aircraft and mobile (including armoured) assets. Among these new changes was the formation of Anti-Aircraft Command which was formed on 1 April 1939, and the 1st Armoured Division formed in 1937. The list below will include the British Army units, colonial units, and those units which were in the process of formation. The list includes units which were in the process of formation, cadre sized, or had no units attached Also included are Territorial Army (TA) and Supplementary Reserve (SR) units.