After an election, the monarch selects as prime minister the leader of the party most likely to command the confidence of the House of Commons, usually by possessing a majority of MPs.

[6] The prime minister, the House of Lords, the Leader of the Opposition, and the police and military high command serve as members and advisers of the monarch on the Privy Council.

The United Kingdom is a constitutional monarchy in which the reigning monarch (that is, the king or queen who is the head of state at any given time) does not make any open political decisions.

This constitutional state of affairs is the result of a long history of constraining and reducing the political power of the monarch, beginning with Magna Carta in 1215.

In practice, the monarch conventionally takes little direct part in governing the country and remains neutral in political affairs.

However, the authority of the state that is vested in the sovereign, known as the Crown, remains the source of executive power exercised by the government.

In addition to explicit statutory authority, the Crown also possesses a body of powers in certain matters collectively known as the royal prerogative.

By long-standing convention, most of these powers are delegated from the sovereign to various ministers or other officers of the Crown, who may use them without having to obtain the consent of Parliament.

What is said in these meetings is strictly private; however, they generally involve government and political matters which the monarch has a "right and a duty" to comment on.

[11] However, the complete extent of the royal prerogative powers has never been fully set out, as many of them originated in ancient custom and the period of absolute monarchy, or were modified by later constitutional practice.

As of 2019, there are around 120 government ministers[12] supported by 560,000[13] civil servants and other staff working in the 24 ministerial departments[14] and their executive agencies.

It requires the support of the House of Commons for the maintenance of supply (by voting through the government's budgets) and to pass primary legislation.

By convention, if a government loses the confidence of the House of Commons it must either resign or a general election is held.

A government is not required to resign even if it loses the confidence of the Lords and is defeated in key votes in that House.

When the government instead chooses to make announcements first outside Parliament, it is often the subject of significant criticism from MPs and the speaker of the House of Commons.

However, some powerful officials and bodies, (e.g. HM judges, local authorities, and the charity commissions) are legally more or less independent of the government, and government powers are legally limited to those retained by the Crown under common law or granted and limited by act of Parliament.

Individual politicians are allowed to sue people for defamation in a personal capacity and without using government funds, but this is relatively rare (although George Galloway, who was a backbench MP for a quarter of a century, has sued or threatened to sue for defamation several times).

[35] The Royal Arms feature on all Acts of Parliament, in the logos of government departments, on the cover of all UK passports (and passports issued in other British territories and dependencies), as an inescutcheon on the diplomatic flags of British Ambassadors, and on The London Gazette.