Download the ‘Is it time to talk about EU membership?’ Report Summary presentation slides.
The need to mitigate the economic damage caused by the UK leaving the EU is rightly driving the UK Government’s ambition for closer UK-EU relations. In the wake of the 2025 Autumn Budget, the UK’s sluggish economic performance and persistent cost of living pressures, combined with the worsening geopolitical context, have precipitated a marked shift in political discourse surrounding UK-EU relations.
Against this backdrop, the UK and EU have been seeking to deliver on commitments made at the UK-EU Summit of May 2025. After years of strained relations, the UK-EU Summit succeeded in drastically improving ‘the atmospherics’ of the UK-EU relationship, but the subsequent detailed negotiations have so far produced mixed results. At best, the failure to reach agreement on the UK’s participation in the EU’s SAFE defence cooperation fund showcased how political ambition hasn’t always translated into common sense results. At worst, it was a warning of the UK Government’s approach nearing the buffers.
With the second post-Brexit UK-EU Summit looming, Best for Britain has analysed public opinion towards each model of UK-EU relationship currently under discussion by all major Westminster political parties, the relative economic benefits of each, and considered the benefits and obligations implied by different models for UK-EU relations.
Our View
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If the tradeoffs and compromises of negotiations with the EU meant it became politically impossible, or impractical, to build beyond the commitments made at the May 2025 UK-EU Summit, then revisiting the UK Government’s negotiation red lines will become not only legitimate, but imperative.
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Were such a rubicon to be passed, neither the options of a UK-EU customs union or joining the EU Single Market are likely to prove politically sustainable policy objectives - even as ‘stepping stones’.
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Membership of the EU would provide the most economic growth of any policy option considered in this report. Unlike the options of a UK-EU customs union, or joining the EU Single Market, membership of the EU would also give the UK ‘decision making’ (as opposed to ‘decision shaping’) rights over EU regulations, and allow UK representation on the Court of Justice of the European Union.
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Ultimately, the data and considerations in this report show that were such a tipping point reached, considerations of economic growth and the balance of rights and obligations suggest that seeking membership of the EU would be the most politically sustainable policy option.
Comparative analysis of the economic benefits of each option
We compare the potential economic growth, rights and obligations, and negotiation timeline implications for all standard options for closer UK-EU relations.
When it comes to the economic growth implications, we determine that EU membership would provide the most economic growth of all options, followed by the UK joining the Single Market. When it comes to ‘a’ UK-EU customs union however, we agree with the consensus that UK GDP growth is likely to be disappointing and of the same order of magnitude as the UK Government’s current approach.
Importantly, we conclude that each option for closer relations with the EU (customs union, Single Market, EU membership) will require a similarly protracted set of negotiations. The main difference between these options - and our determination on their political sustainability - lies in the ‘rights and obligations’ each option entails.
A UK-EU customs union could indeed provide some benefits to the UK goods sector of the economy, but would require the UK to outsource external tariff and trade policy to the EU. This speaks to the public’s concerns about ‘sovereignty’, and given the protracted negotiation timelines and disappointing economic growth, we do not think the benefits of a customs union outweigh its obligations.
Although membership of the Single Market would provide significantly more economic benefits than a customs union, or the UK Government approach, it would require the UK outsourcing many regulations to the EU, with the UK limited to ‘decision-shaping’ rights. Again, this structural weakness speaks to the public’s concerns about ‘sovereignty’. As with the customs union option, we conclude that this arrangement would likely not survive the public discourse that would emerge during the protracted negotiations.
Membership of the EU is similarly vulnerable to concerns about sovereignty, but is the only option to provide the UK with ‘decision making’ rights in the EU. It is the only option to give the UK a substantial say on regulation and trade policy throughout the EU. It will also allow the UK to field judges to the European Court of Justice. Both of these arguments are persuasive assurances that the UK’s sovereignty would be retained.
Of course, both membership of the EU Single Market, and the EU would require the UK to accept Freedom of Movement. With any UK-EU customs union coming as a bolt-on to the current relationship reset, we think concessions on Freedom of Movement are likely even in a UK-EU customs union scenario, and an expanded version of the UK government’s approach.
Assessing the politics of each option, through public opinion polling
Overall 61% support the UK Government’s approach, 53% support rejoining the EU, 49% support a customs union, 46% support the Single Market.
The UK Government’s current approach to UK-EU relations continues to be the political compromise position. However, support for this approach is shallow: just a fifth (19%) express “strong” support, while over twice that number (42%) say they “somewhat support” the strategy. This tells us people are ‘holding their nose’ in support for this compromise position.
After the UK Government’s compromise position, the UK becoming a full member of the EU is the most popular policy option. Around half of all voters (53%) would support UK membership of the EU, with a third (32%) opposed.
There is widespread discontent with the status quo in UK-EU relations, and active opposition to further loosening ties with the EU. Overall, only three in ten (29%) support keeping the UK-EU relationship as it is now, and around three in five (58%) oppose further divergence from the EU.
Around half support the options of joining the Single Market (46%) and customs union (49%), though around a third of respondents say they don't know. Reactions to the UK-EU relationship models considered here can be explained by reference to how people voted at the 2016 referendum, and which political party they support.
The UK Government’s approach creates the compromise position by being the only option to be supported by a majority of both 2016 Remain voters and Leave voters. Their support is shallow however, with over two in five saying they ‘somewhat support’ the approach.
Conversely, keeping the relationship as it is, or further loosening ties, fails to draw majority support from either 2016 Remain or Leave voters. All options for closer relations with the EU (customs union, Single Market, EU membership) break according to the 2016 Referendum vote, with the notable exception that one in five (23%) of Leave voters now support EU membership.
This pattern repeats when looking at responses through the lens of Westminster voting intention.
Britain's relationship with the EU staying as it is unites respondents in their opposition to it. All other options gain majority support from at least one voter group. All other results break according to party lines, defined by how each party’s supporter base voted at the 2016 referendum.
Labour, Liberal Democrats and the Green Party (and by extension the SNP in Scotland, and Plaid Cymru in Wales) supporters, who voted to remain in the 2016 referendum, support all options for closer relations with the EU. They support membership of the EU the most.
On the other hand, Reform UK Supporters, who overwhelmingly voted to leave the EU in 2016, largely oppose all options for closer relations with the EU. They support both further loosening ties, and the UK Government approach, in equal measure.
Floating voters, and Conservative Supporters, fall somewhere between these two poles.
Our report shows that once the UK Government ‘compromise’ position is abandoned, there is almost no difference in support for different UK-EU policy options from Conservative and Reform UK voters. Around two in five (40%) of Conservative Supporters, and one in five (20%) or Reform UK Supporters will back any option for closer UK-EU relations. Those who were holding their nose in support of the UK Government position, are no longer willing to do so, irrespective of the UK-EU relationship model.
However, when looking at 2016 Remain voters, or Labour, Liberal Democrat and Green Party Supporters, we find that EU membership is the only option to receive more support than the UK Government position. Overall, these voter groups do not support a customs union - or membership of the Single Market - more than the UK Government's current approach.
Combined with the reduction in support from Conservative and Reform UK Supporters, neither a customs union, or membership of the Single Market, would provide any political benefit to its proponents overall.
Freedom of Movement
Our polling suggests that opposition to Freedom of Movement is overstated in political discourse. There is strong support for Freedom of Movement in principle, however when the issue is framed as increasing immigration to the UK, that support breaks down according to the general views of the left-leaning pro-European and right-leaning eurosceptic blocs.
Methodology
In this report, we used standard question formulations to measure public sentiment towards six widely understood UK-EU relationship models, where the UK:
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Became a member of the EU again
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Joined the EU’s Single Market
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Negotiated a UK-EU customs union
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Continued with the UK Government approach to UK-EU relations
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Reverted to a UK-EU relationship governed by the Trade and Cooperation Agreement
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Diverged further from the EU
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In this report, we present responses from a survey of 4,368 adults, carried out by YouGov on behalf of Best for Britain between 5th - 10th September 2025. We analysed responses according to 2016 Referendum vote, Westminster Voting Intention, with additional cross-breaks for people who voted Conservative at the 2019 General Election, then Labour in 2024, and people who voted Labour at the 2024 General Election, but are now minded to vote Reform UK.
For each of the polled UK-EU relationships and crossbreaks, we also analysed the change in support and opposition relative to the UK Government approach to UK-EU relations, which we treated as a baseline. The results were used to indicate the likely political cost and benefit of each UK-EU relationship model. We combined this analysis with the relative likely impact of each UK-EU relationship model on UK economic growth (GDP), and the potential rights and obligations each relationship model would entail.
Lastly, we report the findings of a further survey of 4,478 adults carried out by YouGov on behalf of Best for Britain between 8th - 10th March 2026, assessing public attitudes towards Freedom of Movement. We used two different framings of the policy to understand how messages surrounding Freedom of Movement affect support and opposition for the policy. The first framing simply suggested reintroducing ‘Freedom of Movement for all UK and EU citizens’, while the second probed support and opposition in the context of the policy ‘increasing immigration from EU citizens to the UK’.