Following Trenchard's resignation in March 1918 after disagreements with the first air minister, Lord Rothermere, his rival Major General Sir Frederick Sykes was appointed.

With Winston Churchill's post-war appointment as Secretary of State for War and Air, Sykes was moved sideways to head up the nascent Civil Aviation ministry and Trenchard returned as CAS.

[4] By the time the Second World War broke out in 1939, the then occupant of the post, Air Chief Marshal Sir Cyril Newall, had a service that had been undergoing the most rapid of expansions during the British rearmament programs of the late 1930s.

Postwar the RAF was reoriented to perform the dual roles of defending the shrinking British Empire and possibly fighting against the Soviet Union in a Warsaw Pact verses NATO war over Germany and the United Kingdom.

By the early mid-1950s sufficient time had elapsed for officers originally commissioned in the British air services of the First World War to have risen through the ranks to RAF's senior post; Sir John Slessor had originally served in the Royal Flying Corps while Sir William Dickson was commissioned into the Royal Naval Air Service.