History of the United Kingdom: From Medieval Monarchy to Brexit and Beyond

Published on January 17, 2026 and written by Cyril Jarnias

The history of the United Kingdom is that of a state that has been, in turn, a feudal kingdom, the world’s first imperial power, the “workshop of the world,” a pillar of the European Community… before becoming the only sovereign state to leave the European Union. Understanding this journey requires connecting several threads: the slow taming of royal power by Parliament, the rise and decline of the Empire, the Industrial Revolution, the world wars, the devolution of powers to the peripheral nations, and, more recently, the rupture represented by Brexit.

From Medieval Kingdoms to the Birth of the Modern Parliament

Originally, the territory that would become the United Kingdom was fragmented among Anglo-Saxon kingdoms, Celtic kingdoms, and, later, Norman possessions. As early as the Anglo-Saxon era, assemblies like the witan advised the king, foreshadowing the idea of representation. But it was from the central Middle Ages that the embryo of a Parliament began to take shape.

Under the Plantagenets, Parliament became accustomed to involving itself in fiscal and legislative matters. Under Edward I, the “Model Parliament” convened in 1295 already brought together, in a structured manner, prelates, nobles, and representatives of the counties and towns. Over the following centuries, the House of Commons gradually gained importance, eventually becoming the central political arena.

Civil Wars, Revolution, and the Emergence of Constitutional Monarchy

In the 17th century, tensions exploded between the Crown and Parliament. The Stuarts, particularly Charles I, tried to impose a quasi-absolute vision of royalty, relying on the divine right of kings. Charles I even governed without Parliament for more than a decade, until religious, political, and financial conflicts degenerated into civil war.

But the republican experiment was short-lived. After Cromwell‘s death, the balance of power unraveled, and in 1660, the monarchy was restored with Charles II. However, the question of the distribution of powers remained open and resurfaced acutely under James II, accused of wanting to restore an absolute and Catholic royal power.

The “Glorious Revolution” of 1688 then constituted a turning point: James II was overthrown, and the crown was offered to William III and Mary II, on the condition that they accept the Bill of Rights of 1689. This text, complemented by the Act of Settlement of 1701, greatly limited royal authority, guaranteed the role of Parliament, and excluded Catholics from the succession. England became a constitutional monarchy: the king reigned, but political power permanently shifted toward Parliament.

Political Unions: From England to the Whole United Kingdom

At the same time, the state’s territorial framework was transformed. After centuries of Anglo-Scottish wars, the Kingdom of Scotland and the Kingdom of England decided, at the beginning of the 18th century, to unite. The Treaty of Union was concluded in 1706, then ratified in 1707 by the Acts of Union: the Parliaments of Edinburgh and Westminster merged into a new Parliament sitting in London, for the Kingdom of Great Britain. Scotland, however, retained its distinct legal system and its Presbyterian Church, elements that the new state committed to respect.

The Empire: From Atlantic Conquest to the “Sun Never Setting”

In parallel, the United Kingdom projected its power far and wide. Its first colonial ventures date back to the end of the 15th century: Henry VII financed John Cabot’s voyage to the coasts of Newfoundland, while other explorers attempted to find passages to Asia via the north or west. As early as the 16th century, figures like John Hawkins and Francis Drake participated in trade, privateering, and the slave trade.

The 18th century saw confrontation with other colonial powers, particularly France. The Seven Years’ War established British supremacy in North America and India. But the imperial victory concealed a major setback: the revolt of the thirteen colonies led to the independence of the United States in 1783. This shock is often interpreted as the end of the “first” Atlantic empire and the starting point of a “second empire,” turned more toward Asia, Africa, and the Pacific.

In the 19th century, the British Empire experienced its “imperial century”: after the defeat of Napoleon, the British navy dominated the seas, the Pax Britannica imposed relative stability, and London extended its influence through direct conquest as well as through an “informal empire” of finance and trade. India came under direct Crown administration in 1858, after the Sepoy Mutiny; Africa was carved up during the “Scramble for Africa” finalized at the Berlin Conference (1884–85); in Oceania, Australia and New Zealand evolved toward dominion status.

19th Century Historian

At its peak, in the early 1920s, the British Empire was the largest in history: it covered about a quarter of the planet’s land area and administered several hundred million inhabitants. The phrase “the sun never sets on the British Empire” reflects this territorial omnipresence.

Industrial Revolution: The United Kingdom as the “Workshop of the World”

While the Empire brought raw materials and markets, it was the Industrial Revolution that made the United Kingdom the foremost economic power of the 19th century. Between the mid-18th and mid-19th centuries, a series of technical, economic, and social transformations revolutionized the country.

Production exploded: coal, iron, and cotton transformed into textiles grew to unprecedented levels. The United Kingdom became the main exporter of cotton fabrics, to the point that these products represented about half of its exports by the dawn of the 1830s. Machine tools and engineering enabled the construction of bridges, viaducts, and increasingly imposing ships.

Gradually, reactions organized: machine-breaking by the Luddites, social movements, the birth of trade unions, reform campaigns led by philanthropists, writers, and doctors. Parliament began to regulate work (partial limitations on child labor, first factory and mine laws), reform poor relief, and then improve public health with the first urban sanitation acts. In the long term, real wages increased, an urban middle class developed, education progressed, but inequalities remained strong and the social structure reconfigured itself around the ownership of industrial capital more than land.

Democratization and the Assertion of Parliament

Parallel to the Industrial Revolution, political life was transformed. Until the early 19th century, the electoral system was profoundly unequal: “rotten boroughs” with few electors sent members to Westminster, while large industrial towns had no representation. The right to vote was reserved for a small minority of men owning property.

Institutionally, the House of Commons established itself as the center of gravity of the system. The House of Lords saw its powers reduced, notably by the Parliament Acts of 1911 and 1949, which prevented it from permanently blocking laws passed by the Commons. The Prime Minister and his government are now politically responsible to the elected representatives of the people. Furthermore, the supreme judicial function was removed from the House of Lords in favor of a Supreme Court created in 2009, confirming the essentially legislative and oversight role of the two houses.

World Wars, Empire in Crisis, and the Welfare State

The 20th century plunged the United Kingdom into two world conflicts</strong that shook its economy, society, and empire.

During World War I, it mobilized massively: an army of volunteers, then compulsory military service from 1916. The state adopted exceptional powers to organize a war economy, finance the effort through taxation and borrowing, ration supplies, and regulate labor. Human losses were very heavy; major battles like the Somme resulted in tens of thousands of deaths in a few days. The war strengthened the role of the central government and accelerated certain social evolutions: the rise of trade unions, increased participation of women in the workforce, and a challenge to the old political system.

World War II further reinforced the role of the state. Under the leadership of Winston Churchill, the United Kingdom resisted bombings, mobilized all its resources, and coordinated with its dominions and allies. The conflict confirmed the end of British economic supremacy: the United States and the USSR emerged as superpowers, while debt and destruction weighed on reconstruction.

At the same time, the Empire entered its phase of decolonization. The independence of India and Pakistan in 1947, followed by that of multiple territories in Asia, Africa, and the Caribbean, profoundly transformed the United Kingdom’s international standing. The Empire gradually gave way to the Commonwealth, an association of sovereign states more or less linked to London by history and, sometimes, a shared monarchy.

The Thatcher Era: Economic Break and Social Reconfiguration

The late 1970s were marked by stagflation, rising social conflicts, and a challenge to the model of a mixed economy and social compromise. In 1979, Margaret Thatcher came to power with a program that broke sharply with the post-war consensus. Inspired by economic liberal ideas, she focused on fighting inflation, reducing the role of the state in the economy, deregulation, and reinforcing market discipline.

Her governments privatized many public companies (telecommunications, gas, steel, airlines, water, etc.), deregulated finance, and significantly weakened trade unions through a series of laws and a head-on confrontation with the miners. Income tax was reduced, while consumption taxes increased. A portion of the social housing stock was sold to its occupants via the “Right to Buy,” contributing to a rise in individual homeownership but also to a lasting contraction in the supply of social housing.

For its supporters, this strategy is credited with pulling the country out of a relative decline, gaining competitiveness, and modernizing a stagnant economy. For its detractors, it weakened the social fabric, deepened territorial divides, and created an excessive dependence on financial markets. Regardless, the main axes of this transformation — privatizations, deregulation, labor flexibility — were largely maintained by subsequent governments, including Tony Blair’s “New Labour.”

European Integration, from Accession to Brexit

On the European front, the United Kingdom followed an ambivalent path. Initially reluctant about the community project launched by the founding “six” in the 1950s, it eventually applied to join the European Communities and became a member in 1973, alongside Denmark and Ireland. Accession was ratified by Parliament and confirmed by a referendum in 1975, in which a large majority of voters opted to remain in the Community.

In the early 2010s, the European question turned into a major political crisis. Under pressure from part of his own party and the rise of Euroskeptic parties, Prime Minister David Cameron promised a referendum on membership in the European Union. Re-elected in 2015, he carried out this promise. After a limited renegotiation of the terms of membership, the vote in June 2016 saw the victory of the camp in favor of leaving the Union (51.9% of votes) against the camp for remaining.

Brexit: Negotiations, Territorial Fracture, and Economic Consequences

The implementation of Brexit opened a long cycle of negotiations with Brussels and internal political crises. Prime Minister Theresa May triggered the formal exit procedure in 2017 by activating Article 50 of the Treaty on European Union. Parliament, whose sovereignty was reaffirmed by the Supreme Court, had to authorize this move beforehand. Discussions with the EU stumbled over multiple issues, particularly the Irish border: how to leave the single market and the customs union without recreating a physical border between Northern Ireland and the Republic of Ireland, which would threaten the fragile balance of the 1998 peace agreement?

On January 31, 2020, the United Kingdom ceased to be a member of the European Union and entered an eleven-month transition period, during which it remained in the single market and customs union while being excluded from European political bodies. A Trade and Cooperation Agreement, concluded at the end of 2020, governed relations from 2021, covering trade in goods and services, investment, transport, energy, fisheries, police and judicial cooperation, among other things.

Brexit also accentuated internal territorial tensions, particularly in Scotland and Northern Ireland, where the majority of voters had chosen to remain in the Union. The Northern Ireland Protocol, which effectively keeps the region aligned with some of the single market’s rules to avoid a land border, has caused friction within the unionist community and blurs economic borders within the United Kingdom itself. Subsequent adjustments, like the so-called “Windsor Framework” agreement, aim to reduce friction while preserving the absence of a hard border on the island of Ireland.

Devolution: A (Dis)United Kingdom?

Even as the United Kingdom withdrew from a supranational union, the central government has, since the 1990s, transferred an increasing share of its powers to its constituent nations. This process of devolution — sometimes described as “internal autonomy” — is rooted in distinct national histories.

Table 1 – Examples of Devolved Powers in Scotland and Wales

Area	Power in Scotland	Power in Wales
Health	Yes (NHS Scotland)	Yes (NHS Wales)
Education	Yes (distinct system and curriculum)	Yes
Criminal Justice	Yes (specific Scottish law)	Partial, under British legislation
Internal Transport	Yes (regional rail, roads, internal ferries)	Yes (roads, local transport)
Taxation	Income tax rates, certain taxes	Certain taxes, including land and transaction taxes

In Wales, the history is different. Conquered and integrated early into the English crown, the Welsh territory long had no national institutions of its own. It wasn’t until the second half of the 20th century that a Welsh Office was created, then an assembly was instituted following a close referendum. This Assembly, which became the Welsh Parliament (Senedd), saw its powers gradually expanded, moving from an essentially administrative role to genuine legislative and tax-setting capabilities.

England, which represents the vast majority of the population, has no parliament of its own. It remains governed directly from Westminster, although strengthened local authorities (notably the Mayor of London and various metropolitan authorities) have emerged. This asymmetry fuels a recurring debate on the famous “West Lothian question”: should non-English Members of Parliament be allowed to vote on laws affecting only England, when equivalent matters are already the responsibility of devolved assemblies in Wales, Scotland, or Northern Ireland?

Contemporary Political Institutions: Symbolic Monarchy, Sovereign Parliament

Today, the United Kingdom is a constitutional monarchy and a parliamentary democracy. The monarch — currently Charles III — is the head of state, but his powers are essentially symbolic and exercised in accordance with constitutional conventions: opening and closing parliamentary sessions, formally appointing the Prime Minister, granting Royal Assent to laws, etc. The head of government is the Prime Minister, the leader of the party or coalition that holds a majority of seats in the House of Commons.

In partisan terms, political life has historically been structured by the alternation between the Conservative Party and the Labour Party, although other formations — Liberal Democrats, Scottish and Welsh nationalist parties, unionist and nationalist parties in Northern Ireland, Euroskeptic parties — have played or play a significant role. The first-past-the-post electoral system has long favored two-party politics, at the cost of a possible distortion between the number of votes and the number of seats, which fuels recurring debates about electoral reform.

Table 2 – Some Characteristics of the Political System

Element	Description
Type of Government	Constitutional monarchy, parliamentary democracy
Head of State	Monarch (largely symbolic role)
Head of Government	Prime Minister, responsible to the House of Commons
Parliament	Bicameral: Commons (elected), Lords (life peers, some hereditary peers)
National Electoral System	First-past-the-post, 650 constituencies
Main Parties	Conservative, Labour, Liberal Democrats, nationalist/regional parties

After Brexit: Redefining a Place in the World

Since leaving the European Union, the United Kingdom has sought to reconfigure its foreign, trade, and science policies. It concludes new free trade agreements, for example with emerging powers in Asia or with traditional partners like the United States and India. It joined a transpacific trade partnership, betting on opening up to the Indo-Pacific to diversify its trade beyond Europe.

Domestically, the question of the country’s unity remains pending. In Scotland, the argument that the nation was forced out of the European Union against the will of its electoral majority fuels the demand for a new independence referendum. In Wales, the idea of increased autonomy is gaining ground, although independence sentiment remains lower. In Northern Ireland, the debate over the border and the constitutional future of the territory has been revived, as demographic and political balances reconfigure.

A History of Continuity and Ruptures

From the Magna Carta to Brexit, via the creation of the modern Parliament, the meteoric rise of the Empire, the Industrial Revolution, the world wars, decolonization, the welfare state, the Thatcherization of the economy, devolution, and exit from the European Union, the history of the United Kingdom appears as a constant interplay between institutional continuity and political ruptures.

On one hand, a red thread of stability: the monarchy has been interrupted only once, Parliament boasts centuries of age and sovereign power, the major structures of the state evolve slowly through successive reforms rather than revolutions. On the other, major discontinuities: the transformation of the Empire into the Commonwealth, the shift from an agrarian to an industrial then service economy, the mutations of the party system, the internal reconfigurations caused by devolution, the redefinition of the relationship with Europe.

Far from being merely a linear narrative of imperial grandeur and decline, the history of the United Kingdom is that of a state that has continually adjusted its institutions and alliances to the changing constraints of its environment, seeking to reconcile age-old traditions — monarchy, parliamentarism, common law — with adaptation to the economic, social, and geopolitical realities of the moment. It is this tension between permanence and change that continues to structure, even today, debates about its identity, its internal borders, and its place in the world.