Page "Prime Minister of the United Kingdom" Paragraph 54

Under this form of government, called the Westminster System, the Sovereign is Head of State and titular head of Her Majesty's Government.

She selects as her Prime Minister the person who is able to command a working majority in the House of Commons, and invites him to form a government.

As the actual Head of Government, the Prime Minister selects his Cabinet, choosing its members from among those in Parliament who agree or generally agree with his intended policies.

He then recommends them to the Sovereign who confirms his selections by formally appointing them to their respective offices.

Led by the Prime Minister, the Cabinet is collectively responsible for everything the government does.

The Sovereign does not confer with its members privately about policy or attend its meetings.

With respect to actual governance, the monarch has only three constitutional rights: to be kept informed, to advise, and to warn.

In practice this means that the Sovereign reviews state papers and meets regularly with the Prime Minister, usually weekly, when she may advise and warn him regarding the proposed decisions and actions of Her Government.