[1] Prior to the outbreak of the Second World War, concerns about British forces being understrength led in 1936 to the creation of the post of Minister for Coordination of Defence by Prime Minister Stanley Baldwin.

The post was abolished by Baldwin's successor Neville Chamberlain in April 1940.

The post was created in response to previous criticism that there had been no clear single minister in charge of the prosecution of the war.

In 1946, the post became the only cabinet-level post representing the military, with the three service ministers—the Secretary of State for War, the First Lord of the Admiralty, and the Secretary of State for Air—now formally subordinated to the Minister of Defence.

In 1964, the creation of a single, merged Ministry of Defence and the abolition of the separate service ministries in the UK led to the creation of the new post of Secretary of State for Defence, more popularly known as Defence Secretary.