How to Research the History of UK and EU Relations

Researching the history of UK and EU relations is easiest when you combine a clear timeline with primary sources, scholarly explanations, and competing national perspectives. This guide shows you how to plan the investigation, verify claims, and build a balanced account from postwar cooperation to Brexit and beyond.

1. Define the question before you search

“UK and EU relations” covers more than seven decades, so begin by narrowing the purpose of your research. A focused question produces better evidence than a general search for “everything about Brexit.”

Possible research questions include:

• Why did the United Kingdom initially hesitate to join European integration?
• What changed between the UK’s first application and its eventual membership in 1973?
• How did the 1975 referendum differ from the 2016 referendum?
• Why did the UK often seek special arrangements within the European Community and later the EU?
• How did the relationship change after the Brexit referendum?
• What were the effects of the Withdrawal Agreement and the Trade and Cooperation Agreement?

Write your question as a single sentence. Then identify three limits:

1. Time period: for example, 1945–1973, 1973–1992, 1993–2016, or 2016–present.
2. Theme: trade, sovereignty, migration, security, party politics, public opinion, or constitutional law.
3. Geographic perspective: the UK government, an EU institution, an individual member state, Northern Ireland, Scotland, Wales, or England.

These limits prevent a common research problem: treating “Britain,” “the UK,” “the European Community,” and “the EU” as interchangeable throughout the entire period. The European Economic Community began in 1957, while the European Union was created by the Maastricht Treaty in 1993. Use the name that was historically accurate for the period you are describing.

2. Build a working timeline first

Before reading detailed sources, create a timeline with dates, events, decisions, and unresolved questions. This gives you a structure for evaluating later claims.

Period	Key development	Research question
1945–1957	Postwar cooperation and the creation of European communities	Why was the UK outside the first institutions?
1961–1973	Applications, vetoes, negotiations, and membership	What changed politically and economically?
1975–1992	Membership debate, budget disputes, and treaty developments	How did British participation evolve?
1993–2015	EU membership, opt-outs, enlargement, and domestic disagreement	Which powers were shared or retained?
2016–2020	Referendum, negotiations, and withdrawal	What did “Leave” legally require?
2021 onward	New UK–EU relationship	Which issues remained unresolved?

Important entries include the Treaty of Rome in 1957, the UK’s first application in 1961, Charles de Gaulle’s vetoes in 1963 and 1967, accession in 1973, the 1975 referendum, the Single European Act, the Maastricht Treaty, the 2016 referendum, the Article 50 process, the Withdrawal Agreement, the end of the transition period, and the Trade and Cooperation Agreement.

Do not treat a timeline as an argument. It is an organizing tool. The same event may be interpreted differently depending on whether you are studying economic integration, national sovereignty, party strategy, or public opinion.

3. Start with reliable overview sources

Use an overview to understand vocabulary and sequence, but do not rely on one overview for your entire article. Good starting points include:

• Parliamentary research briefings from the UK Parliament or House of Commons Library.
• Publications from the European Parliament, European Commission, or Council of the EU.
• University history departments and research centres.
• Academic books from established historians and political scientists.
• Official treaty and legislation databases.
• Reputable public broadcasters and major newspapers for contemporary reporting.

Overview sources are useful for discovering dates, people, treaties, and keywords. They are less useful when they make broad claims without showing evidence. For example, a statement that the UK “always opposed Europe” is too vague to be meaningful. Ask: which government, which policy, which decade, and which meaning of “Europe”?

When you find an unfamiliar term, record it in a research glossary. Useful terms include European Coal and Steel Community, European Economic Community, European Community, acquis communautaire, qualified majority voting, rebate, opt-out, Schengen Area, Article 50, Withdrawal Agreement, and Trade and Cooperation Agreement.

4. Find primary sources for major claims

Primary sources show what governments, institutions, politicians, and voters actually said or decided at the time. They should support the most important factual claims in your research.

Useful primary sources include:

• Treaty texts and protocols.
• Parliamentary debates and committee reports.
• Government white papers, speeches, and official statements.
• Referendum legislation and results.
• European Council conclusions and Commission documents.
• Court judgments from relevant national or European courts.
• Contemporary newspaper reports and televised interviews.
• Declassified cabinet papers and diplomatic records.
• Statistical releases on trade, migration, budgets, and public opinion.

For UK material, search the UK Parliament website, parliamentary archives, The National Archives, government publications, and the British Newspaper Archive where available. For EU material, consult EUR-Lex, the European Parliament archives, the European Commission’s document collections, and the Historical Archives of the European Union.

Read primary sources critically. A government statement is evidence of the government’s position, not automatic proof that its description was complete or accurate. A campaign leaflet can show persuasive language and political priorities, but it may simplify or exaggerate. A treaty can establish legal obligations, but it does not by itself explain public attitudes.

For each source, record:

• Who created it?
• When and where was it created?
• What audience was intended?
• What decision, belief, or interest shaped the language?
• Which facts can it establish directly?
• What does it leave out?

5. Compare UK and EU perspectives

A balanced account should not describe the relationship only from Westminster’s viewpoint. The UK had its own political divisions, and the European institutions also contained different national interests.

Compare at least two perspectives for each major turning point. For the 1960s, examine British economic and political concerns alongside French objections and the positions of the other applicant countries. For the 1970s, compare the UK government’s case for membership with the arguments of the 1975 “Yes” and “No” campaigns. For Brexit, distinguish between the UK government, the European Commission, the European Council, the European Parliament, the devolved governments, Northern Ireland’s political parties, and different business or civic groups.

Also separate the following concepts:

• The EU institutions: bodies such as the Commission, Parliament, Council, and Court.
• The member states: national governments that negotiate collective decisions.
• The public: voters whose views may differ from their government’s policy.
• The UK: a state containing different political and national communities.

This distinction matters because “the EU decided” may conceal disagreement between member states, while “Britain wanted” may conceal differences between governments, parties, regions, and generations.

6. Investigate treaties and legal changes carefully

Treaties are central to the history of UK–EU relations, but they can be difficult to read. Do not begin by trying to read every page. First identify the provisions relevant to your question.

A practical method is:

1. Find the official treaty text.
2. Read the preamble for stated goals.
3. Search the document for terms related to your topic.
4. Check protocols, declarations, and annexes.
5. Read an authoritative legal or parliamentary explanation.
6. Compare the original provision with later amendments.

For membership-era research, look at accession arrangements, budget provisions, the Single European Act, Maastricht provisions, and later treaty changes. For Brexit-era research, distinguish the referendum result from the legal process that followed. The referendum expressed a political instruction, but withdrawal required negotiations, parliamentary decisions, an agreement, and arrangements for future cooperation.

Be especially careful with the words “opt-out,” “veto,” “control,” and “single market.” An opt-out can apply to one policy area rather than the entire EU framework. A veto may refer to a specific decision-making rule rather than an unlimited power. The single market concerns rules intended to support the movement of goods, services, people, and capital; it is not identical to a free-trade agreement.

7. Research public opinion and political campaigns

Referendums and elections are important, but a result alone does not explain why people voted as they did. Look at polling trends, campaign arguments, regional variation, age and education patterns, economic conditions, and party competition.

Use reputable polling archives and election studies where possible. Check the wording of each question, the fieldwork dates, the sample, and whether the poll measured voting intention, approval, or retrospective opinion. Do not compare percentages from surveys that asked different questions.

Campaign material should be studied as political communication. Record the main promises and fears, then investigate whether later evidence supports, qualifies, or contradicts them. Avoid presenting campaign claims as established facts. A useful structure is:

• What did the campaign claim?
• What evidence was available at the time?
• What was uncertain?
• What happened later?
• Which effects can be attributed to the policy, and which had other causes?

8. Verify economic and social claims

Economic claims about UK–EU relations are often the most contested. Use data from statistical agencies, central banks, international organizations, and peer-reviewed research. Check definitions before comparing figures.

For example, “trade with the EU” could mean goods only, goods and services combined, gross exports, value added, or the EU’s share of total UK trade. “Migration” may refer to gross inflows, net migration, a specific citizenship group, or a particular period. State exactly what your number measures.

When comparing before and after Brexit, consider confounding factors such as the COVID-19 pandemic, energy prices, global supply disruptions, exchange rates, wars, and changes in domestic policy. A change after 2020 is not automatically caused by Brexit.

Prefer sources that publish methodology and downloadable data. Keep a note beside every statistic with its unit, date, geographic coverage, and original source. Round figures consistently, and do not imply precision that the data does not support.

9. Handle difficult or conflicting sources

Disagreement is normal in this subject. When two credible sources differ, do not immediately choose the one that matches your preferred interpretation.

First check whether they are answering different questions. One source may discuss legal authority, while another discusses practical influence. One may measure short-term effects, while another examines a longer period. They may also use different definitions or data periods.

If the disagreement remains, present it transparently. Explain what each source claims, what evidence each uses, and whether one has a stronger method for your specific question. Use cautious language such as “researchers disagree,” “the evidence is mixed,” or “the effect is difficult to isolate.” This is more useful than forcing a false certainty.

Watch for common problems:

• Anachronism: applying today’s EU structure to an earlier period.
• Presentism: judging past decisions only by later outcomes.
• False continuity: assuming every UK government had the same policy.
• False equivalence: treating a documented fact and an unsupported claim as equally reliable.
• Selective quotation: using a sentence without its surrounding qualification.
• Causal overreach: claiming one event caused a complex outcome without testing alternatives.

10. Organize notes and write the final account

Create a source table or spreadsheet with columns for date, event, claim, source, source type, quotation or page reference, perspective, and confidence level. Separate facts from interpretations. Mark gaps with specific questions rather than filling them with guesses.

A strong article usually follows a chronological argument with thematic signposts:

1. Explain the postwar context and early European institutions.
2. Describe why the UK stayed outside initially and why it later applied.
3. Cover accession and the 1975 referendum.
4. Explain later treaty changes, disputes, and domestic politics.
5. Analyze the 2016 referendum and withdrawal negotiations.
6. Describe the post-Brexit relationship and identify continuing debates.

Use dates when a policy changed, and define technical terms on first use. Link to original documents whenever practical. If a claim is disputed, identify the dispute instead of hiding it in vague language.

Finally, read your draft once as a fact-checker and once as a reader unfamiliar with the subject. The fact-checking pass should verify dates, names, treaty titles, referendum figures, and statistics. The reader pass should ask whether each transition is clear and whether the article distinguishes evidence from opinion.

Practical limitations of the research

No single archive contains the whole history. Official sources may protect institutional interests, campaign material may be deliberately persuasive, polling may miss groups or measure unstable opinions, and academic interpretations may change as new records become available. Some information is also difficult to compare because the UK and EU use different categories or reporting periods.

The best research therefore combines source types rather than searching for a supposedly neutral source. Use official documents for decisions and legal texts, archives for contemporary context, statistics for measurable outcomes, and scholarship for interpretation. Keep the scope manageable, show where uncertainty remains, and make every major conclusion traceable to evidence.