The CGS reports to the Chief of the Defence Staff (CDS) and, as a Service COS, has a right of direct access to the Secretary of State and the Prime Minister.

Responsibile for: The title was also used for five years between the demise of the Commander-in-Chief of the Forces in 1904 and the introduction of Chief of the Imperial General Staff in 1909.

During the Second World War, General Brooke focused on grand strategy, and his relationships, through the Combined Chiefs of Staff with his American counterparts.

He was also responsible for the appointment and evaluation of senior commanders, allocation of manpower and equipment, and the organisation of tactical air forces in support of land operations of field commanders; he also had primary responsibility for supervising the military operations of the Free French, Polish, Dutch, Belgian, and Czech units reporting to their governments in exile in London.

Brooke vigorously allocated responsibilities to his deputies, and despite the traditional historical distrust that had existed between the military and the political side of the War Office, he got along quite well with his counterpart, the Secretary of State for War, first David Margesson and later, Sir James Grigg.