Chiefs of Staff Committee

The Chiefs of Staff Committee (CSC) is composed of the most senior military personnel in the British Armed Forces, who advise on operational military matters and the preparation and conduct of military operations. The committee consists of the chief of the defence staff, who is the chairman and professional head of the armed forces, and the vice-chief of the defence staff, who is the vice-chairman and deputy professional head of the armed forces.

Source: Wikipedia — Chiefs of Staff Committee (CC BY-SA 4.0)