The Brexit Files - from Referendum to Reset

Aug 21, 2026

Impartial, research-based analysis brings together leading scholars on UK–EU relations for the fifth anniversary of the UK leaving the EU. The work traces the Brexit process from pre-referendum UK roles and euroscepticism through referendum design, campaign dynamics, results, and key agreements. It then evaluates post-Brexit impacts across politics, law, regulation, economy, trade, investment, sectors, labour and migration, energy and climate, foreign policy, and public administration, before outlining the future UK–EU relationship.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages142

Reading Time5 h 58 min

AccessFree to download

Contributors

Introduction

Part I: The Brexit process

Before Brexit: the UK as a member state

Euroscepticism before the referendum

Cameron’s renegotiation with the EU

Designing the referendum

Leave and Remain: the Brexit referendum campaign

The referendum result

The Northern Ireland question

The Withdrawal Agreement and the Trade and Cooperation Agreement

The 2017 General Election

The 2019 General Election

The May Government’s Brexit policy

The Johnson Government’s Brexit policy

The EU’s Brexit strategy

The role of Parliament during the Brexit process

The role of the courts during the Brexit process

Part II: Brexit impact and aftermath

Dealing with the EU post-Johnson: Truss and Sunak EU Policy

Brexit and the Conservative Party

Brexit and the Labour Party

The public and Brexit

Evaluating ‘Bregret’: The views of Leave voters

Brexit and the law

Regulatory divergence

Brexit impact: the economy

Brexit impact: trade

Brexit impact: investment

Brexit impact: manufacturing and industry

Brexit impact: services

Brexit impact: agriculture

Brexit impact: environment

Brexit impact: labour market and migration

Brexit impact: energy and climate

Brexit impact: foreign policy

Brexit and the machinery of government

Brexit and the civil service

Brexit and devolution

Brexit and Northern Ireland

The Starmer government’s EU policy

The EU after Brexit

Part III: The future

The future of the UK-EU relationship

THE BREXIT FILES FROM REFERENDUM TO RESET FOREWORD For the past decade, UK in a Changing Europe has provided impartial, researchbased analysis on a number of issues, but most particularly on UK-EU relations. Since before the 2015 General Election, we have evaluated those relations, traced and explained the tortuous Brexit process, and attempted to assess the impact that Brexit has had on the country. This report brings together some of the best scholars working on these issues to consider a number of these questions on the 5th anniversary of the UK ceasing tobe a member of the European Union. I am incredibly grateful to all those who have given their time to contribute to it, and to their patience and forbearance in coping with and responding to what must have seemed at times like an endless stream of comments and queries from the UKICE team. Talking of whom, the UKICE team have pulled out all the stops to make this report as comprehensive and easily readable as possible, while not only contributing individual pieces but also collectively writing the final section. I am grateful for, and proud of, their work. I hope you find what follows useful and informative. As ever, do get in touch should you have any comments, questions, or suggestions for future reports. 28 January 2025 Professor Anand Menon Director, UK in a Changing Europe CONTENTS Contributors 5 Introduction 7 Part I: The Brexit process Before Brexit: the UK as a member state 11 Euroscepticism before the referendum 14 Cameron’s renegotiation with the EU 17 Designing the referendum 20 Leave and Remain: the Brexit referendum campaign 23 The referendum result 26 The Northern Ireland question 30 The Withdrawal Agreement and the Trade and Cooperation Agreement 33 The 2017 General Election 36 The 2019 General Election 40 The May Government’s Brexit policy 43 The Johnson Government’s Brexit policy 46 The EU’s Brexit strategy 49 The role of Parliament during the Brexit process 52 The role of the courts during the Brexit process 55 Part II: Brexit impact and aftermath Dealing with the EU post-Johnson: Truss and Sunak EU Policy 61 Brexit and the Conservative Party 64 Brexit and the Labour Party 67 The public and Brexit 70 Evaluating ‘Bregret’: The views of Leave voters 73 Brexit and the law 77 THE BREXIT FILES: FROM REFERENDUM TO RESET 3 Regulatory divergence 80 Brexit impact: the economy 83 Brexit impact: trade 86 Brexit impact: investment 90 Brexit impact: manufacturing and industry 94 Brexit impact: services 97 Brexit impact: agriculture 101 Brexit impact: environment 104 Brexit impact: labour market and migration 107 Brexit impact: energy and climate 111 Brexit impact: foreign policy 114 Brexit and the machinery of government 117 Brexit and the civil service 120 Brexit and devolution 123 Brexit and Northern Ireland 126 The Starmer government’s EU policy 129 The EU after Brexit 132 Part III: The future The future of the UK-EU relationship 137 4 THE BREXIT FILES: FROM REFERENDUM TO RESET CONTRIBUTORS David Bailey, Professor of Business Economics, University of Birmingham Tim Bale, Professor of Politics, Queen Mary University London Catherine Barnard, Professor of European Union and Employment Law, University of Cambridge, and Senior Fellow, UK in a Changing Europe Matt Bevington, Practice Director, Global Counsel Ben Brindle, Researcher at the Migration Observatory, Oxford University Pierre Bocquillon, Associate Professor in European Politics, University of East Anglia John Curtice, Professor of Politics Strathclyde University, and Senior Research Fellow at both the National Centre for Social Research and UK in a Changing Europe Cleo Davies, Assistant Professor in Politics and International Relations, Forward College Geoffrey Evans, Professor of the Sociology of Politics, Oxford University Robert Ford, Professor of Political Science, University of Manc

FAQs

What is the main scope of The Brexit Files - from Referendum to Reset?

It assembles research on UK–EU relations and the Brexit journey, then assesses Brexit’s impacts and discusses future options for the UK–EU relationship.

Which topics are covered in Part I of the report?

Part I traces Brexit’s evolution: pre-referendum UK membership context, euroscepticism, referendum design and campaign, the result, the Northern Ireland question, major agreements, general elections, government strategies, and institutional roles of Parliament and courts.

How does the report assess Brexit’s aftermath in Part II?

Part II evaluates political and social effects, legal dimensions, regulatory divergence, and sector-by-sector outcomes including the economy, trade, investment, manufacturing, services, agriculture, environment, labour and migration, energy and climate, and foreign policy, plus governance machinery and devolution.

Aug 21, 2026

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