The Future of UK-EU Relations: Ten Years After the Brexit Referendum

Briefing note on conferences in London and Brussels organised by Flint Global and UK in a Changing Europe on 23 and 30 June 2026

State of UK-EU relations 

The overall tone of the conference was relatively optimistic on the current direction of travel in the post-Brexit relationship. Most speakers agreed that relations have improved significantly since the immediate post-Brexit period, supported by cooperation on Ukraine and the Labour government's "reset" agenda, but with continuing caution on the EU side. 

UK Minister for EU relations Nick Thomas-Symonds presented the UK Government's approach since the 2024 election as one of pragmatic cooperation. He argued that the UK's relationship with the EU should no longer be treated as an "identity issue" but instead focus on delivering practical benefits.  

While trust between the UK and EU remains limited, speakers agreed it is gradually improving with the passage of time. Nevertheless, Flint founding partner Sir Simon Fraser argued that there is "not enough trust on the EU side regarding the UK, and not enough genuine interest on the UK side regarding the EU". UK Ambassador to the EU Lindsay Appleby-Croisdale noted that "predictability is not the same as trust", but establishing predictable arrangements is an important first step towards a more productive relationship.  

While speakers cautioned against expecting a transformational UK-EU Summit (when it is rearranged), there was broad optimism that negotiations on a sanitary and phytosanitary (SPS) agreement, emissions trading systems linkage and a youth mobility scheme were within reach. 

However, these should be seen as incremental progress rather than a wholesale “reset” of the relationship, particularly given the political and economic trade-offs of significantly closer UK alignment with the EU. Nick Thomas-Symonds made clear that a future Labour government would remain committed to the 2024 manifesto and continue pursuing deeper cooperation but within existing political red lines. Former EU Brexit negotiator Michel Barnier was adamant that for the EU, protecting the Single Market was sacrosanct and could not be compromised. 

Security as the primary driver of closer relations 

One of the clearest messages was that defence and security provide the most immediate political rationale for closer UK-EU cooperation. Russia's invasion of Ukraine, uncertainty over future US engagement in European security and wider geopolitical instability have reshaped priorities. As Fabian Zuleeg (European Policy Centre) observed, Brexit remains economically significant, but it is "not Europe's dominant political concern".  

As EU governments are increasingly focused on responding to shared external threats, there is growing consensus that the UK has a role to play in the continent’s response. Charles Fries, Deputy Secretary-General of the European External Action Service, said "there is no European security without the UK, and there is no UK security without Europe."  

EU Defence Commissioner Andrius Kubilius took this further by proposing that the EU and UK join forces in a “European Defence Union” to work on shared challenges, including reducing reliance on the United States. Other speakers repeatedly stressed that cooperation should be framed around addressing common security challenges and that this should extend beyond defence into cyber security, organised crime, sanctions, maritime security and critical infrastructure protection.  

Some speakers highlighted the gap between rhetoric and action , particularly following the failed negotiations for the UK to join the EU’s SAFE programme. Steven Everts (EU Institute for Security Studies) warned that "the politics of the UK-EU relationship are advancing more slowly than the geopolitics of the world around us", while Julian King (Flint Global) argued that maintaining momentum is vital if the two sides are to avoid diverging on issues including regulation of emerging technologies and economic security. 

Economic cooperation: a shift towards economic security 

While speakers debated the scale of Brexit's economic impact, discussion focused less on revisiting those arguments and more on the way forward and the urgency of better relations to promote growth.  

Most accepted that the UK leaving the Single Market and Customs Union has increased trade friction and weakened investment, particularly for goods trade. Former Italian Prime Minister Enrico Letta also pointed out that Europe “lost a decade on financial market integration” and that the EU’s attempts to replace London as a financial hub post-Brexit ultimately “benefitted only New York and Wall Streat”.  

However, the emphasis has since shifted towards strengthening economic resilience through cooperation on supply chains, industrial strategy, energy security and critical technologies. Amanda Brooks (Department for Business and Trade) argued that "the biggest opportunity is economic resilience and security", while Anthony Gooch-Gálvez (European Round Table for Industry) suggested political attention should move beyond resolving individual trade barriers towards cooperation in defence industries, innovation and dual-use technologies. 

Incremental, practical improvements – including an SPS agreement, addressing an upcoming cliff-edge on electric vehicle battery rules of origin, mutual recognition of conformity assessments and professional qualifications – were widely viewed as realistic measures that could deliver useful but limited tangible benefits for businesses without fundamentally reopening the Brexit settlement. 

Regulatory alignment as the central trade-off 

A recurring theme was that deeper cooperation will require greater regulatory alignment. Speakers broadly agreed that closer access to EU markets comes with accepting EU rules in specific sectors, although opinions differed on whether this was desirable.  

Catherine Barnard (University of Cambridge) argued that while the UK can influence EU legislation during consultation, meaningful decision-making influence is inevitably lost outside EU membership. Anand Menon (UK in a Changing Europe) recalled an EU official's observation that the UK appears to want "a Single Market in goods with Europe and a single market in services with the United States". Several speakers suggested this balancing act will become increasingly difficult as competition between US and EU regulatory models intensifies, particularly in AI and emerging technologies.  

Former Brexit negotiator Lord David Frost insisted that the UK's priority should remain preserving national policy autonomy rather than pursuing closer integration. Arguing the costs of Brexit have been overstated by economists, he said the focus should be on using the freedoms Brexit provides to strengthen the UK's economy and governance rather than pursuing dynamic alignment with the EU. 

Risks and Outlook 

It was widely noted that political uncertainty in the UK and EU Member States will have a major impact on the future of the UK-EU relationship in the long-term. Future governments could seek to reopen or reverse agreements reached under the current reset – whether a led by Reform UK, Rassemblement National or the Alternative for Germany.  

Tim Montgomerie (Flint Global) said that he expected Reform UK to pursue “pragmatic adjustments” to any agreements made with the EU if they were to form the next Government. He stressed that this would be necessary to balance out sensible cooperation with the democratic wishes of the British people. 

Speakers said that regulatory divergence was happening and would continue unless actively managed. This would in some circumstances be encouraged – with Tim Montgomerie suggesting “much of the European [pro-regulation] ethos still permeates our system of government”. Several participants questioned whether Whitehall has sufficient capacity to sustain increasingly complex sector-by-sector relationships with the EU. 

Catherine de Vries (University of Amsterdam) argued that debates around sovereignty need to evolve, suggesting cooperation on shared cross-border challenges should increasingly be seen as strengthening rather than weakening national sovereignty. Enrico Letta similarly argued that both sides should focus on building "something useful for people and businesses, not purely ideological." 

Overall, the conference reflected a shift in thinking. Brexit is increasingly viewed as the context within which the relationship now operates rather than the defining issue itself. For the time being, the future of UK-EU relations is likely to be driven less by debates over membership and more by the search for shared strategic interests in security, defence and economic resilience. Though there will be hard and complex negotiations, as geopolitical pressures mount, the conference's central message was that closer UK-EU cooperation in some areas is becoming less a political choice than a strategic necessity. 

This blog was written by Founding Partner and Interim Chair Simon Fraser, Associate Director Miro Guzzini, and Director Kathryn Watson, with additional input from the wider Flint team.