After attending RAF Staff College in 1937 he was attached to the Air Staff. In 1939 he was made Senior Operations Officer for Palestine and Transjordan. On 17 May 1941 he was appointed senior RAF officer on Crete overseeing the reception of units after their withdrawal from Greece. To aid him in this task he was allocated two RAF squadrons from Egypt, 30 and 205 to bolster the fighters already stationed on the island. But following the German Invasion of Crete this action turned into the defence of the island. Unable to convince the Army Commander of the need to defeat the invaders from the air, the island fell and Beamish ordered the RAF squadrons to withdraw to Egypt on 19 May. Beamish remained on Crete to assist General Freyberg, both men escaping the island aboard a Sunderland in late May. He was then appointed Senior Air Staff Officer first at Western Desert Air Force, then at North African Tactical Air Forces and then at Second Tactical Air Force before progressing to the roles of Air Officer Commanding No. 44 Group and then No. 45 Group.