[3] It is composed of various units that support Cabinet committees and coordinate the delivery of government objectives via other departments.

This is still its principal role, but since the absorption of some of the functions of the Civil Service Department in 1981 the Cabinet Office has also helped to ensure that a wide range of Ministerial priorities are taken forward across Whitehall.

Immediately to the west Dorset House (1700) connects the front of the building to William Kent's Treasury (1733–36), which faces out onto Horse Guards Parade.

The latter is built over the site of the Cockpit, used for cock fighting in the Tudor period, and subsequently as a theatre.

Significant renovations between 2010 and 2016 converted many of the floors to open plan and created new office space.