|Headquarters||Main Building, MOD, London|
|Parent agency||Ministry of Defence|
The Defence Secretariat was formed in 1952 from central administrative divisions of the Ministry of Defence. In 1964 the three existing service departments of state the Department of Admiralty, the Air Ministry and the War Office were unified into the Ministry of Defence it absorbed the secretariat branches from the Admiralty, War Office and Air Ministry. In 1985 it was replaced by the Office of Management and Budget.
The Defence Secretariat was formed partly from the pre-1964 central administrative divisions of the Ministry of Defence and partly by the direct transfer of some branches from the Admiralty, War Office and Air Ministry. Most of the new, unified ministry was organised on a joint rather than an integrated or functional basis in that sections of the naval, general (army) and air staffs with similar responsibilities remained separate within their own departments but were brought together in joint committees. The consequent co-ordinating role was performed by the Defence Secretariat which acted as the nerve centre of the whole ministry.Initially, it was organised under a second permanent under secretary with three deputy under secretaries of state, responsible for programmes and budget, policy and administration, respectively.
Below them were ten assistant under secretaries of state and subjects covered included the defence programme and budget, research and development, advice and aid to the naval, general and air staffs, policy, matériel (equipment), and general functions such as press and public relations. In 1968, as a reflection of the change from three single-service ministers of state to two functional ministers, the Defence Secretariat was re-organised under two, new, second permanent under secretaries of state for administration and equipment. The number of deputy under secretaries was increased to five and they were responsible for personnel and logistics, policy and programmes, civilian management, finance and equipment. The re-organisation of the Ministry of Defence on 2 January 1985 ended the Defence Secretariat as such, although its functions continued to be carried out by several directorates in the new Office of Management and Budget.
- "Ministry of Defence: Defence Secretariat Branches and their Predecessors: Registered Files". discovery.nationalarchives.gov.uk. Kew, London: National Archives UK. 1952–2009. Retrieved 18 September 2019.
- National Archives UK.
- National Archives UK.
- "Ministry of Defence: (1952–2009). Defence Secretariat Branches and their Predecessors: Registered Files". discovery.nationalarchives.gov.uk. Kew, London: National Archives UK.