Brexit’s hidden legacy: The constitutional revolution nobody voted for

Yuliia Bond

This article is based on the Wales Governance Centre event, Wales and the Referendum on EU Membership: A Decade On, held at the Pierhead Building in Cardiff on 23 June.

The panel included Professor Jo Hunt, Dr Jac Larner and Dr Rachel Minto, and reflected on the decade since the referendum, including the UK-EU relationship, implications for Wales at the start of the Seventh Senedd, changes in UK governance, devolution, public opinion and Wales’ constitutional future.

It was sponsored by Peredur Owen Griffiths MS.

Devolution, power and the Brexit Wales never wanted

Ten years after the Brexit referendum, the debate is often framed as a question of winners and losers.
Was Brexit economically successful? Has it delivered greater sovereignty? Has it strengthened Britain’s position in the world?

These questions dominate political discussion, yet they risk obscuring a deeper constitutional story.

For Wales, Brexit was never simply about leaving the European Union. It was also about the future of devolution, the distribution of power within the United Kingdom, and the relationship between Cardiff and Westminster.

Indeed, one of the strongest arguments emerging from recent Wales Governance Centre analysis is that Brexit’s most significant consequences may not ultimately concern Britain’s relationship with Brussels at all. They may concern the constitutional relationships within the United Kingdom itself.

The irony is difficult to ignore.

Brexit was presented as a project to “take back control”. A decade later, one of the most important constitutional questions concerns where that control ultimately went. Did powers returning from Brussels flow naturally to Cardiff, Edinburgh and Belfast in areas that were already devolved? Or did Brexit trigger a reassertion of authority by Westminster?

The answer depends partly on political perspective. But the fact that the question remains contested tells us something important about the constitutional significance of Brexit itself.

Wales and Europe: A different relationship

One of the recurring themes throughout the event was that Wales’ relationship with the European Union differed significantly from that of the UK as a whole.

Economically, Wales was a net beneficiary of EU membership. While the UK overall contributed more to the EU budget than it received back, Wales received substantial support through European Structural Funds and regional development programmes. European investment became visible across Welsh communities through infrastructure projects, regeneration schemes, university research initiatives, training programmes and economic development projects.

The blue-and-gold European flag was not an abstract symbol. For many communities, it was attached to roads, buildings, employment programmes and local investment.

There was also a political dimension.

Long before Brexit, Wales sought to cultivate a distinct European presence. The Welsh Government established representation in Brussels and actively participated in European networks. Membership of the European Union provided Wales with access to political spaces in which smaller nations could exercise influence beyond what their population alone might suggest.

This helps explain why much of the Welsh political establishment supported continued EU membership.

Yet Wales voted Leave.

That result created one of the defining tensions of the Brexit era in Welsh politics. How could Welsh institutions respect the referendum outcome while simultaneously seeking to protect what they viewed as Wales’ economic and constitutional interests?

The Brexit Wales Proposed

One of the most significant, and often overlooked, documents of the Brexit period was the Welsh Government’s 2017 publication Securing Wales’ Future. Produced jointly by Welsh Labour and Plaid Cymru, the document outlined a coherent alternative vision of Brexit. Its significance lies not simply in its proposals but in what it reveals about the nature of the Brexit debate itself.

Looking back, there is a tendency to talk about Brexit as though there was only one possible destination.

The event challenged this assumption. There were many possible Brexits.

The Welsh Government’s preferred model involved continued participation in the Single Market, continued membership of the Customs Union and continued engagement with a range of European programmes and institutions. In effect, it advocated a considerably softer Brexit than the one ultimately pursued.

That vision lost. But its existence remains politically important. It demonstrates that constitutional preferences differed significantly across the UK. Brexit was not merely a negotiation between Britain and Europe. It was also a contest between competing visions of Britain’s future within Britain itself.

The eventual outcome reflected political choices made at Westminster rather than a constitutional consensus across the nations of the UK.

The hidden constitutional framework of devolution

Perhaps the most important intellectual contribution from the event was the argument that devolution had been built within a constitutional environment shaped by European Union membership. This point is often missed in public debate.

The Senedd, Scottish Parliament and Northern Ireland Assembly were created during the late 1990s. At the time, EU membership was assumed. Nobody designing those institutions was asking how devolution would operate outside the European Union.

As a result, European law performed a constitutional function that often went unnoticed. Agriculture operated within the Common Agricultural Policy. Environmental regulation was heavily influenced by European directives. Food standards, state aid, competition policy and numerous other areas were governed through shared European frameworks.

The existence of these frameworks reduced the need for the UK to develop sophisticated mechanisms for managing internal divergence. European law effectively acted as a common rulebook. The devolved governments could pursue different priorities, but they did so within broadly shared parameters.

For two decades, this arrangement worked largely because nobody seriously challenged the assumptions on which it rested. Brexit removed those assumptions.

Only then did policymakers discover how many constitutional questions had never actually been answered.

The question nobody had needed to ask

What happens when devolved governments want to use their powers differently? This sounds like an obvious question. Yet before Brexit it rarely generated major constitutional controversy. The reason is simple. EU membership reduced the scope for divergence while simultaneously providing mechanisms for managing it.

Brexit transformed a theoretical question into a practical one. Suppose Wales adopts stricter environmental standards than England. Suppose Scotland introduces different food regulations.
Suppose Northern Ireland maintains closer regulatory alignment with the European Union. Can goods and services continue to circulate freely across the United Kingdom? If the answer is yes, devolved regulation may become less effective. If the answer is no, barriers may emerge within the UK market.

This tension lies at the heart of post-Brexit constitutional politics. It is not a technical problem. It is a constitutional one.

Common frameworks: The road not taken

One of the most fascinating discussions during the event concerned what might have happened instead.
The original post-Brexit response centred on the development of Common Frameworks. These were designed to allow governments to negotiate how divergence would be managed in areas previously governed by EU law. The philosophy was collaborative. Governments would discuss differences. Disputes would be managed politically. Agreements would emerge through cooperation.

For many within the Welsh and Scottish Governments, this approach reflected the spirit of devolution.
It recognised that divergence was not necessarily a problem to be eliminated. Indeed, one could argue that divergence is often the purpose of devolution. Different governments should be able to pursue different policy choices.

However, Common Frameworks were never the only constitutional vision available.

The UK Internal Market Act and a different vision of the Union

The UK Internal Market Act 2020 represented a fundamentally different answer to the same problem.
Supporters argue that the Act provides essential economic infrastructure.

The UK is a single state. Businesses expect access to a single market. Consumers expect consistency. Internal barriers are economically costly. From this perspective, the legislation protects economic integration.

Critics view the Act differently. For them, the issue is not primarily economic but constitutional. The concern is that the legislation prioritises market access over devolved autonomy. The principles of mutual recognition and non-discrimination mean that products lawfully sold in one part of the UK generally cannot be excluded elsewhere.

The crucial issue is not whether devolved governments retain legislative competence. They do. The issue is whether they retain meaningful regulatory autonomy. This distinction between formal power and practical power lies at the centre of contemporary constitutional debate.

A government may retain authority on paper while finding its ability to shape outcomes constrained in practice. Whether that constitutes centralisation remains contested. But the debate itself has become one of the defining constitutional arguments of the post-Brexit era.

Scotland’s Deposit Return Scheme and the politics of power

The Scottish Deposit Return Scheme became the most visible example of these tensions. On the surface, the policy concerned recycling. Consumers would pay a small deposit on drinks containers and recover the money upon return. Hardly revolutionary.

Yet the proposal became a constitutional flashpoint. The reason was that the dispute was never really about recycling. It was about authority. Could Scotland pursue a distinct regulatory path? Under what conditions? Who decides when divergence is acceptable? Who acts as the referee when governments disagree?

The collapse of the scheme transformed what might have been a routine environmental policy into a symbol of wider constitutional tensions. Supporters of the UK Government viewed the episode as evidence of the need for common market rules. Critics viewed it as evidence that devolved autonomy was becoming constrained.

The debate continues because both sides are ultimately arguing about different visions of the Union.

Brexit’s hidden constitutional legacy

The most important lesson from the first decade after Brexit may be that constitutional systems often reveal their true character only when subjected to pressure.

For twenty years, devolution operated within a relatively stable environment. European membership provided an overarching framework. Intergovernmental disputes remained manageable. Certain constitutional assumptions were never seriously tested.

Brexit changed that. It exposed tensions that had previously remained hidden. It forced governments to confront questions they had never needed to answer. It revealed the extent to which devolution had developed within an EU framework. And it opened a new debate about whether Brexit represented a decentralisation of power or a reconfiguration of it.

Sovereignty, Identity and the Future of the Union

Once the United Kingdom left the European Union, the debate was no longer simply about trade, borders or regulation. It became a debate about authority. Who decides? Whose consent matters? What limits exist on Westminster’s power? How should disagreements between the nations of the UK be resolved? And perhaps most importantly: what does devolution actually mean in a post-Brexit state?

These questions sit at the heart of the constitutional arguments that have emerged over the past decade.
Brexit did not create them. But it forced them into the open.

The constitutional safeguard that failed its biggest test

No constitutional principle better illustrates this than the Sewell Convention. For most of its existence, the convention attracted relatively little public attention. It sat quietly in the background of the UK’s territorial constitution. The principle appeared simple. Westminster would not normally legislate on devolved matters without the consent of the devolved legislatures.

That phrase – “not normally” – became one of the most scrutinised constitutional phrases of the Brexit era.

Before Brexit, many politicians and commentators assumed the convention represented a meaningful constitutional safeguard. After all, it appeared in the devolution legislation itself. Legislative consent motions had become an established feature of the constitutional landscape. Consultation and cooperation had become part of the political culture of devolution.

Yet Brexit subjected the convention to pressures it had never previously experienced. The Welsh Government objected to aspects of Brexit legislation. The Scottish Government objected to aspects of Brexit legislation. Legislative consent was withheld. Westminster legislated anyway. Legally, there was little controversy. Politically, there was enormous controversy.

What Brexit revealed was that the convention functioned primarily as a political restraint rather than a legal one. When political consensus existed, the convention worked. When political consensus broke down, the convention offered far less protection than many assumed. This distinction matters because it exposed a deeper reality about the constitutional position of devolved institutions.

Parliamentary sovereignty returns to centre stage

For decades, parliamentary sovereignty had largely disappeared from everyday political discussion.
Constitutional lawyers understood its significance, but for many citizens the practical realities of sovereignty seemed increasingly remote.

The creation of devolved legislatures, the growth of Welsh political institutions and the normalisation of devolution created a perception that power had been permanently redistributed. Brexit forced a reconsideration of that assumption.

At its core, the United Kingdom remains a system based on parliamentary sovereignty. Unlike federal states such as Germany, Canada or the United States, the UK possesses no entrenched constitutional division of powers protected by a constitutional court. The Senedd is powerful. The Scottish Parliament is powerful. But Westminster remains legally supreme.

For some, Brexit simply revealed a constitutional reality that had always existed. For others, it demonstrated the limits of a constitutional system built primarily upon political understandings rather than legal protections.

The significance of Brexit therefore lies not in changing the doctrine of parliamentary sovereignty but in exposing its practical consequences.

For perhaps the first time since devolution began, large numbers of people confronted the implications of Westminster’s ultimate constitutional authority.

Political Constitutionalism Meets Reality

The United Kingdom has traditionally relied on what constitutional scholars call political constitutionalism. In many countries, constitutional disputes are resolved through courts. Formal legal protections define relationships between different levels of government. The constitution acts as a referee.

Britain developed differently. Historically, the UK relied heavily on conventions, understandings, political relationships and mutual restraint. The system assumed that political actors would generally behave constitutionally because constitutional behaviour was politically expected. Brexit challenged this assumption.

The constitutional machinery functioned exactly as designed. The problem was that different actors held fundamentally different views about what constitutional behaviour required. The result was not constitutional breakdown. It was constitutional disagreement. And disagreement revealed just how much of the UK’s constitutional architecture depends upon political culture rather than legal constraint.
For Wales, this has become one of the most important constitutional lessons of the Brexit era.

The great recentralisation debate

Perhaps no question generates more disagreement among constitutional scholars than whether Brexit has produced a form of recentralisation.

The debate is often presented too simplistically. Critics of the post-Brexit settlement argue that powers returning from Brussels have frequently become subject to new forms of Westminster oversight.

Supporters argue that all functioning states require mechanisms to preserve economic integration and policy coherence. Both positions contain elements of truth. The more interesting question concerns how we define power itself.

If the Senedd retains legislative competence but operates within a framework that constrains the practical consequences of divergence, has power increased or decreased? The answer depends largely upon what one believes devolution is intended to achieve.

If devolution exists primarily to allow policy variation, then post-Brexit arrangements may appear restrictive. If devolution exists within the context of a unified economic state, then those same arrangements may appear necessary. This is why the debate is unlikely to disappear. It reflects fundamentally different understandings of the Union.

One vision prioritises territorial autonomy. The other prioritises market integration. Brexit forced these competing visions into direct confrontation.

Labour’s reset: Constitutional change or political change?

The election of a Labour Government in 2024 introduced a new political dynamic. Relations between Westminster and the devolved governments became noticeably less confrontational. The language of partnership returned. The rhetoric of cooperation returned.

The creation of the Council of Nations and Regions symbolised an attempt to improve territorial governance. Yet one of the most important observations made during the event was the distinction between political change and constitutional change. The tone changed. The architecture largely did not.
The UK Internal Market Act remains. Parliamentary sovereignty remains. The fundamental constitutional structure of the post-Brexit settlement remains intact.

This does not mean the reset is meaningless. Politics matters. Relationships matter. Trust matters.
Intergovernmental relations often function better when governments are willing to cooperate. But constitutional scholars tend to distinguish between changes in behaviour and changes in structure.
The former may be temporary. The latter tend to endure.

Whether Labour’s reset ultimately produces lasting constitutional reform remains an open question.

Europe Moved On Faster Than Britain

One of the most striking observations from last week’s event concerned the differing ways Britain and Europe experienced Brexit.

Within the UK, Brexit dominated political debate for years. Governments fell. Prime Ministers resigned.
Political parties fractured. Referendum arguments continued long after the referendum itself.

In Brussels, the experience was remarkably different. There was certainly intense engagement during the negotiations. Yet once the withdrawal process concluded, Brexit quickly became one issue among many.
The European Union did not unravel. The anticipated domino effect never materialised. Instead, attention shifted elsewhere. COVID-19. Energy security. Strategic competition. Migration. Economic competitiveness. And most significantly, Russia’s invasion of Ukraine.

The contrast is revealing. While Britain often continued to define itself through Brexit, Europe increasingly treated Brexit as a settled fact. That divergence in perspective continues to shape UK-EU relations today.

The Brexit Europe never saw coming

Another important theme from the discussion was that the European Union itself has changed significantly since 2016. British debates often assume Europe remained static while Britain transformed.

The reality is quite different. The EU Britain left no longer exists in precisely the same form. The 2024 European Parliament elections demonstrated this clearly. Right-wing and nationalist parties increased their representation significantly. Collectively they now account for more than a quarter of the Parliament.

This has implications for future policymaking. Environmental ambitions have encountered greater resistance. Migration debates have become increasingly prominent. Questions of competitiveness, industrial policy and security have moved up the agenda.

The significance for Wales lies in recognising that any future relationship with Europe will be shaped by a different European political landscape than the one that existed during the referendum. Brexit froze many British assumptions about Europe. Europe itself continued evolving.

Ukraine, security and the return of geopolitics

Perhaps the most profound change in European politics since Brexit has been the return of hard security concerns. Russia’s invasion of Ukraine transformed European strategic thinking. Questions of defence, military capability and geopolitical coordination moved rapidly to the centre of political debate.
This has created an interesting paradox.

Britain may have left the European Union, but it remains deeply involved in European security.
Indeed, one could argue that geopolitical realities have made cooperation more important rather than less important. The growing significance of the E3 – Britain, France and Germany – reflects this reality.

When Britain was an EU member, these states were often viewed as the Union’s most influential powers.
Today they increasingly cooperate outside formal EU structures on matters of security and foreign policy.

For Wales, this matters because it demonstrates that Brexit did not remove Britain from Europe.
It changed the institutions through which European cooperation takes place. Geography, history and security continue to bind Britain to the continent regardless of constitutional arrangements.

Beyond the ‘Left Behind’ narrative

The polling evidence presented at the event challenged one of the most influential interpretations of Brexit.

For years, Brexit was commonly portrayed as a revolt by communities that felt economically abandoned.
The phrase “left behind” became central to political commentary. Yet more recent research suggests a more complicated picture.

Economic explanations remain important. However, they are insufficient on their own. One particularly striking finding highlighted during the discussion was that wealthier voters were often more likely to support Leave than many commentators expected.

This does not invalidate economic explanations. Rather, it suggests that the referendum cannot be understood purely through economic deprivation. Something deeper was shaping political behaviour.
Increasingly, researchers point towards identity.

Identity and the Brexit Divide

One of the strongest predictors of Brexit attitudes was not income but identity. How individuals understood themselves often shaped how they understood Europe. Attitudes towards Britishness, Welshness, Englishness and Europeanness frequently influenced political preferences. This matters because identity operates differently from economics.

Economic circumstances can change relatively quickly. Identity tends to be more durable. It helps explain why Brexit remains politically significant even after the practical realities of withdrawal have become familiar.

The referendum was never simply a debate about economics. It was also a debate about sovereignty, belonging and national identity. These questions remain politically powerful today.

Constitutional sorting and Wales’ political future

Perhaps the most fascinating finding from the polling evidence concerns the emergence of constitutional sorting. Increasingly, attitudes towards Europe and attitudes towards the constitutional future of Wales appear to be clustering together.

Supporters of rejoining the European Union are increasingly likely to support greater Welsh autonomy and, in some cases, Welsh independence. Supporters of Brexit are increasingly likely to favour stronger unionism and, among some groups, abolition of the Senedd.

This does not mean the categories overlap perfectly. Many exceptions exist. Nevertheless, a clear trend is emerging. Two constitutional debates are gradually becoming intertwined. Wales’ place within the United Kingdom. Britain’s place within Europe. The political consequences of this development may become one of the defining features of Welsh politics over the next decade.

Demographic change and the future electorate

Perhaps the most intriguing observation from the polling discussion concerned how political attitudes change over time. The conventional assumption is that societies change because people change their minds. The evidence suggests something more subtle. Many Leave voters remain Leave voters.
Many Remain voters remain Remain voters. The electorate itself, however, changes continuously.

Older generations leave the electorate. Younger generations enter it. As a result, constitutional politics may be shaped less by persuasion and more by demographic replacement. For long-term debates about Europe, devolution and the future of the Union, this distinction is crucial. The future may depend less on changing opinions and more on changing generations.

The questions Brexit left behind

Ten years after the referendum, the most important constitutional questions remain unresolved. Can devolution function effectively within the structures created by Brexit? Does the UK require stronger constitutional protections for devolved government? Can political cooperation compensate for the absence of legal safeguards? Has Brexit strengthened the Union or exposed its vulnerabilities? And what balance should exist between economic integration and democratic autonomy? Brexit did not answer these questions.

In many respects, it simply made them impossible to avoid.

The long constitutional shadow of Brexit

The referendum answered one question. Should the United Kingdom remain a member of the European Union? The country answered no. What followed was not the end of constitutional debate but the beginning of a new one.

Brexit exposed assumptions that had underpinned devolution for two decades. It revealed tensions between parliamentary sovereignty and territorial autonomy. It transformed discussions about governance, legitimacy and identity. And it increasingly linked debates about Europe to debates about the future of the Union itself.

For Wales, Brexit’s most enduring legacy may not be the relationship Britain left behind. It may be the constitutional questions that remain ahead. Ten years later, those questions are still shaping the political future of Wales, the United Kingdom and the Union itself.