Her Majesty's Government is the executive political authority for the United Kingdom as a whole. At its heart is the Cabinet, a grouping of senior Ministers of the Crown, headed by the Prime Minister. Members of the Government are political appointees, and are usually drawn from one of the two Houses of Parliament. In addition to the heads of the Departments of State (most of whom carry the title of Secretary of State), the Government also includes junior ministers (who bear the title of Under Secretary of State, Minister of State, or Parliamentary Secretary), whips (responsible for enforcing party discipline within the two Houses), and Parliamentary Private Secretaries (political assistants to ministers).
When the Sovereign is the King, the Government is referred to as His Majesty's Government; likewise, when there are joint Sovereigns, the Government is known as Their Majesties' Government.
The Prime Minister (or "PM") is the head of the Government. Since the early twentieth century the Prime Minister has held the office of First Lord of the Treasury, and in recent decades has also held the office of Minister for the Civil Service.
The Prime Minister is asked to form a Government by the Sovereign. Usually this occurs after a general election has altered the balance of party political power within the House of Commons. The Prime Minister is expected to have the confidence of the House of Commons; this usually means that he or she is the leader of the polical party holding the majority of the seats in the Commons. Since at least the 1920s the Prime Minister himself is also expected to be a Member of Parliament (i.e. member of the House of Commons). The Prime Minister retains office until he or she dies or resigns, or until someone else is appointed; this means that even when expecting to be defeated at a general election, the Prime Minister remains formally in power until his or her rival is returned as an MP and asked in turn to form a Government.
By convention, the Prime Minister and his or her Government is expected to resign if losing a vote in the House of Commons that has been asserted in advance by the Government as a matter of confidence; for example, if major legislation is rejected. The same applies if the Government is defeated by an actual Commons vote of "no confidence". An alternative option for the Prime Minister in either of these circumstances is to ask the Sovereign for a dissolution of Parliament, in effect allowing the electorate itself to approve or disapprove of the Prime Minister's policy. A request for dissolution is usually granted; however, in certain circumstances the request may be refused, in which case the Prime Minister would again be expected to resign.
The existence and basis of appointment of the office is a matter of constitutional convention rather than of law. Because of this, there are no formal qualifications for the office. However, a small number of Acts of Parliament do make reference to the Prime Minister, and since the 1930s office has carried a salary in its own right.
The Prime Minister is often an extremely powerful figure within the political system; the office has been said by some to be an "elected dictatorship", and some Prime Ministers have been accused of being "presidential". A weak Prime Minister may be forced out of office (i.e. forced to resign) by his or her own party, particularly if there is an alternative figure within the party seen as a better choice.
Cabinet and other ministers
Membership of the Cabinet is not defined by law, and is only loosely bound by convention. The Prime Minister and (if there is one) the Deputy Prime Minister are always members, as are the three most senior ministerial heads of Departments of State: the Secretary of State for Foreign and Commonwealth Affairs (commonly known as the Foreign Secretary), the Chancellor of the Exchequer (i.e. the minister responsible for finance), and the Secretary of State for the Home Department (commonly known as the Home Secretary). Most of the other heads of departments are usually members of the Cabinet, as well as a small number of junior ministers.
Ministers of the Crown are formally appointed by the Sovereign upon the "advice" of the Prime Minister. Ministers are bound by the convention of collective responsibility, by which they are expected to publicly support or defend the policy of the Government, or else resign. They are also bound by the less clearly defined convention of individual responsibility, by which they are responsible to Parliament for the acts of their department. Ministers are often called upon to resign who either by their own actions, or by those of their department, are perceived in some manner to have failed in their duty; however, it usually takes sustained criticism over a period of time for both a minister to feel compelled to resign, and for the Prime Minister to accept that resignation. Occasionally a minister offers his or her resignation, but the Prime Minister retains them in office.
Parliamentary Private Secretaries are also bound by the principle of collective responsibility, even though they hold no ministerial responsibility and take no part in the formation of policy; the position is seen as an initial stepping-stone towards being offered ministerial office.
Her Majesty's Most Honourable Privy Council is a ceremonial body of advisors to the Sovereign. The Privy Council is used as a mechanism for maintaining ministerial responsibility for the actions of the Crown; for example, royal proclamations are approved by the Privy Council before they are issued. All senior members of the Government are appointed to be Privy Counsellors, as well as certain senior members of the Royal Family, leaders of the main political parties, the archbishops and senior bishops of the Church of England, and certain senior judges.
The Privy Council is headed by the Lord President of the Council, a ministerial office usually held by a member of the Cabinet. By convention the Lord President is also either the Leader of the House of Commons, or the Leader of the House of Lords, with responsibility for directing and negotiating the course of business in the respective House.
Meetings of the Privy Council are usually extremely short, and are rarely attended by more than a bare minimum of Privy Counsellors.