The Prime Minister is supported in making decisions about the allocation of ministerial responsibilities by the Cabinet Secretary. The Cabinet Secretariat provide advice to the Cabinet Secretary on this issue. There is no set number of staff devoted to this issue and those involved have other duties in the Cabinet Secretariat.
The Cabinet Office has not recently prepared or commissioned reports into machinery of government changes. A report was published in 2002 on the creation of the Department for Environment, Food and Rural Affairs. A copy of this has been placed in the Libraries of both Houses.