The Cabinet Office
As the name suggests, the Cabinet Office is the government department that tends to the needs of the present Prime Minister and his or her Cabinet, primarily taking on the role of intermediary between the various Ministers and their own departments. Among its stated aims are objectives such as to coordinate government policy inter-departmentally and to ensure all Cabinet activity falls within the Ministerial codes of conduct.
Historically an important talking-shop for Cabinet colleagues to discuss the key decisions of the day, the Cabinet Office's role has broadened over recent decades and now includes the promotion of government priorities to the whole of Westminster. In practical terms this means getting departments to work together towards a common goal, such as meeting government targets in health, education or law and order.
Among the various positions in the Cabinet Office, that of Cabinet Secretary has a particular importance. The Cabinet Secretary is always the head of the Civil Service and so has a special role in the maintenance of the finely-balanced relationship between ministers and civil servants.
Prominent members of the Cabinet also take on Cabinet Office roles, such as Culture Secretary Hazel Blears who is the current Minister without Portfolio.
For practicality's sake, this crucial department is situated adjacent to the seat of power in Downing Street, Cabinet meetings being a regular occurrence, and the historic building even boasts relics of Henry VIII.