Prior to 1942, all Armed Forces Headquarters employees were deployed in Services Headquarters and Secretariats of the then Department of Defence, Finance(Defence) and War. Though they had common nomenclature, they were treated as separate cadres and were controlled locally by the above departments and branches of Services Headquarters.
In 1942, all these cadres were brought under one single authority by creation of the post of Chief Administrative Officer in the then War Department. The first CAO took over on 01 August 1942. See old pic and documents.
The office of Chief Administrative Officer (CAO) is responsible for providing civilian manpower and infrastructural support to the Services Headquarters and the Headquarter offices of Inter-Services Organisations (ISOs) under Ministry of Defence.
Chief Administrative Officer is the Cadre Controlling Authority and Head of the Department for about 12,000 AFHQ civilian employees.