Field Marshal Alan Francis Brooke, 1st Viscount Alanbrooke,, was a senior officer of the British Army. He was Chief of the Imperial General Staff (CIGS), the professional head of the British Army, during the Second World War, and was promoted to field marshal on 1 January 1944. As chairman of the Chiefs of Staff Committee, Brooke was the foremost military advisor to Prime Minister Winston Churchill, and had the role of co-ordinator of the British military efforts in the Allies' victory in 1945. After retiring from the British Army, he served as Lord High Constable of England during the Coronation of Queen Elizabeth II in 1953. His war diaries attracted attention for their criticism of Churchill and for Brooke's forthright views on other leading figures of the war.

The Chief of the General Staff (CGS) has been the title of the professional head of the British Army since 1964. The CGS is a member of both the Chiefs of Staff Committee and the Army Board; he is also the Chair of the Executive Committee of the Army Board. Prior to 1964, the title was Chief of the Imperial General Staff (CIGS). Since 1959, the post has been immediately subordinate to the Chief of the Defence Staff, the post held by the professional head of the British Armed Forces.