Her Majesty's Government, commonly referred to as HM Government (HMG), the British Government or Whitehall (where most of its departments are located), is the central government of the United Kingdom.
The Government is led by the Prime Minister, who selects all the remaining Ministers. The Prime Minister and the other most senior Ministers belong to the supreme decision-making committee, known as the Cabinet. The Government Ministers are all members of Parliament, and are accountable to it. The Government is dependent on Parliament to make primary legislation,which means that in practice a government must seek re-election at least every five years.The monarch selects as Prime Minister the leader of the party most likely to command a majority in Parliament.
Under the uncodified British constitution, executive authority lies with the monarch, although this authority is exercised only by, or on the advice of, the Prime Minister and the Cabinet.The Cabinet members advise the monarch as members of the Privy Council. They also exercise power directly as leaders of the Government Departments.
Source: http://en.wikipedia.org/wiki/Government_of_the_United_Kingdom Date last accessed: 11/11/13