The British monarch is head of state. Executive power, however, is wielded by a prime minister, who is head of government, and a committee of ministers called the cabinet. The prime minister is usually the leader of the majority party in the House of Commons. By custom, cabinet ministers are selected from among members of the two houses of Parliament. Cabinet ministers are also among the members of the Privy Council, the traditional, but now largely ceremonial, advisory body to the Crown.

In principle, the “Crown in Parliament” is supreme. This means that legislation passed by Parliament, which consists of the House of Commons (elected directly by the people) and the House of Lords (made up of hereditary peers and appointive members—archbishops, senior bishops, law lords, and life peers) becomes law upon royal assent. In practice, legislation is dominated by the prime minister and the cabinet, who initiate virtually all proposed bills and who are politically responsible for the administration of the law and the affairs of the nation. Fiscal legislation is always initiated in the House of Commons, and other legislation almost always. Since the Parliament Act of 1911, the House of Lords has been unable to block fiscal legislation. By the terms of the Parliament Act of 1949, the Lords may not disapprove other bills if they have been passed by two successive annual sessions of the Commons. The power of the Crown to veto legislation has not been exercised in over 280 years.

The House of Lords is composed of hereditary peers and peeresses, 2 Anglican archbishops, and 24 bishops who serve as “lords spiritual” as long as they retain their authority, and life peers whose titles are not hereditary. Life peers include lords of appeal, who make up the court of last resort on matters that can be brought to the House of Lords, and an increasing number of lords created in recognition of distinguished service (often in politics). The Peerage Act of 1963 enables a lord to relinquish his title for life and thus to become eligible for election to the House of Commons and for selection as prime minister. The full House of Lords numbers more than 1200, but average daily attendance is less than 400. Only three members are required for a quorum. Bills from the House of Commons are passed to the House of Lords for discussion. Although no vote from the House of Lords is necessary to pass legislation, the body often suggests revisions and provides a forum for debate free from party politics.

Members of the House of Commons are elected from geographical constituencies. The voting age for British subjects was lowered to 18 in 1969. Those not eligible for election to the Commons include members of the House of Lords, selected clergy, government contractors, sheriffs, and certain designated election officials. The basis of representation depends on the total number of seats agreed on by a process unique to the House of Commons and on the total population of the nation. In Great Britain, each constituency approximates a population of 60,000. In Northern Ireland, with 17 representatives, the population base is somewhat larger. Total membership of the Commons now numbers 651. Forty members are required for a quorum. By law, the life of a Parliament is five years unless dissolved earlier or extended by special statute in times of war or national emergency. Parliament is dissolved by the sovereign at the end of its five-year term or on advice of the prime minister. All members of the House of Commons are then subject to the general election.

Although, in theory, any member of Parliament may propose a bill, most legislation is initiated by the cabinet minister responsible for the department concerned. Acts passed by Parliament tend to be worded in general terms; they are implemented, with specification of detailed provisions, by Orders in Council, prepared by the minister responsible and promulgated by proclamation of the Crown. The cabinet, under the doctrine of collective responsibility, acts as a unit. The defeat of important legislation or a vote of no confidence usually brings about the resignation of the entire cabinet and a general election. The prime minister may drop individual cabinet members entirely or reassign them as preferred. This power helps to maintain the prime minister's leadership and is exercised in most governments periodically. Ministers may resign their posts without leaving the Parliament.

Minor parties in the early 1990s included the Scottish Nationalist, Plaid Cymru (Welsh Nationalist), Ulster Unionist, Social Democratic, Communist, and Green parties. The Liberal Party, which provided governments periodically for decades, lost electoral support and merged with dissidents from Labour and the Conservatives to form the Liberal Democrat Party. In the general election of 1992, minor parties won 44 seats from the total of 651 in the House of Commons.

The government of Great Britain is unitary in structure. Thus, the powers of local government derive from Parliamentary acts, and responsibility for the overall administration of the country rests with specified cabinet ministries. Local authorities, however, are essentially independent. The present structure was established by a Local Government Act in 1972. Shire counties have county, district, and parish councils. Metropolitan areas have joint authorities, district councils, and parish councils. District council members are elected for staggered four-year terms; most other councilors are elected for three-year terms. England has 39 counties and 7 metropolitan areas, including Greater London, which has a special government structure. Wales has 8 counties, and Scotland has 9 counties which are called regions. Northern Ireland has only district-level government, with 26 districts. There is no constitutional division of powers between central and local authorities in Britain, but local units are responsible for police and fire services, education, libraries, highways, traffic, housing, building regulations, and environmental health. In April 1990 a change in financing local government reduced local rates or property taxes and substituted a community charge, labeled a “poll tax.” This unpopular tax produced intense political debate and riots in London; it was replaced in 1992 with a property-based tax. The same legislation called for competitive bidding for local services such as garbage collection and street cleaning.

Most practicing general physicians in Great Britain are part of the National Health Service, although some also have private patients. Established in 1948, the service provides full, and in most cases, free medical care to all residents. Patients, who may opt for a particular physician, pay minimal charges for prescriptions, adult dental treatment, eyeglasses and dentures, and some locally administered services, such as vaccinations. Most dentists, pharmacists, and medical specialists take part in the service. Each general practitioner may have no more than 3500 registered patients under the plan, for each of whom he or she receives a fee. The National Health Service is financed through general taxation, with national insurance payments contributing some 14 percent of the total cost, and patients' fees contributing 4 percent.

The British army is controlled by the Defence Council through an Army Board composed of both civilian and military members. Active members of the army are volunteers who enlist for 22 years of service. Under a plan introduced in 1972, however, army personnel may choose to serve for only three years. In the early 1990s the army numbered 134,600 men and women. A citizen national reserve force, the Territorial Army, has an establishment of more than 68,500 and may be called out in times of emergency. Northern Ireland has a special reserve force of 5700, the Ulster Defense Regiment, which gives part-time support to the regular army.

The Royal Navy is governed by the Admiralty Board under the secretary of state for defense. Naval craft in the early 1990s included 2 aircraft carriers, 12 destroyers, 25 frigates, 20 (including 16 nuclear-powered) submarines, and many auxiliary vessels. The navy was in the process of reducing its fleet size in the mid-1990s. Navy personnel numbered about 59,300.

The Royal Flying Corps was established in 1912; in 1914 the naval wing of the corps became the Royal Naval Air Service, and in 1918 the two were amalgamated as the Royal Air Force. Since 1964 the air force has been under the unified Ministry of Defence. It is administered by the Air Force Board, headed by the secretary of state for defense. The air force is organized into home and overseas commands. In the early 1990s Royal Air Force personnel numbered some 80,900.

More than 85,000 British troops were deployed abroad in 1990. Contingents were serving in Germany, Belize, Brunei Darussalam, the Falkland Islands, Gibraltar, Hong Kong, and Cyprus.