Secretary of State for Defence The Secretary of State for Defence , also referred to as the Defence Secretary , is the senior Government of the United Kingdom minister in charge of the Ministry of Defence , chairing the Defence Council . It is a position . The position was created in 1964 as successor to the posts of Minister for Coordination of Defence ( 1936 – 1940 ) and Minister of Defence ( 1940 – 1964 ) . Office holders . Minister for Co - ordination of Defence ( 1936 – 1940 ) . The position of Minister for Co - ordination of Defence was a - level position established in 1936 to oversee and co - ordinate the rearmament of Britain ' s defences . The position was established by Prime Minister in response to criticism that Britain ' s armed forces were understrength compared to those of Nazi Germany . This campaign had been led by Winston Churchil and many expected him to be appointed as the new minister , though nearly every other senior figure in the National Government was also speculated upon by politicians and commentators . Despite this , Baldwin ' s choice of the Attorney General Sir Thomas Inskip provoked widespread astonishment . A famous comment made in response to Inskip ' s appointment was " This is the most cynical appointment since Caligula made his horse a consul " . The appointment is now regarded as a sign of caution by Baldwin who did not wish to appoint someone like Churchill who would have been interpreted by foreign powers as a sign of the United Kingdom preparing for war , as well as a desire to avoid taking on board a controversial and radical minister . In 1939 Inskip was succeeded by First Sea Lord Lord Chatfield . When the Second World War broke out , the new Prime Minister Neville Chamberlain formed a small War Cabinet and it was expected that Chatfield would serve as a spokesperson for the three service ministers , the Secretary of State for War , the First Lord of the Admiralty and the Secretary of State for Air ; however , political considerations resulted in all three posts being included in the Cabinet , and Chatfield ' s role proved increasingly redundant . In April 1940 the position was formally wound up and the functions transferred to other Ministers . Colour key ( for political parties ) : Ministers of Defence ( 1940 – 1964 ) . The post of Minister of Defence was responsible for co - ordination of defence and security from its creation in 1940 until its abolition in 1964 . The post was a level post and generally ranked above the three service ministers , some of whom , however , continued to also serve in Cabinet . On his appointment as Prime Minister in May 1940 , Winston Churchill created for himself the new post of Minister of Defence . The post was created in response to previous criticism that there had been no clear single minister in charge of the prosecution of World War II . 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 . Colour key ( for political parties ) : Secretaries of State for Defence ( 1964 – present ) . The post of Secretary of State for Defence was created on 1 April 1964 . The former Cabinet positions of First Lord of the Admiralty , Secretary of State for War and Secretary of State for Air ( responsible for the Royal Navy , British Army and Royal Air Force respectively ) were incorporated into it and the offices of the Admiralty , War Office and the Air Ministry were abolished and their functions transferred to an expanded Ministry of Defence . Colour key ( for political parties ) : In popular culture . The fictional Secretary of State for Defence , Michael Lee , was a minor character in Abigail Gibbs ' acclaimed novel The Dark Heroine ( series ) .