The Cabinet Office is a department of the Government of the United Kingdom responsible for supporting the Prime Minister and Cabinet of the United Kingdom. The department was formed in December 1916 from the secretariat of the Committee of Imperial Defence under Sir Maurice Hankey, the first Cabinet Secretary. Since then it has developed various units to support Cabinet committees and to co-ordinate the delivery of government objectives via other departments. It currently has just over 1,000 staff, most of whom work in Whitehall. - Source: Wikipedia