Forget about the economy. Britain’s referendum will be decided by concerns about sovereignty and foreigners. These are the two issues that rock the boat of European governments in the late 2010s, and that inspired the Danes to reject EU justice cooperation at a vote in December 2015. Denmark’s long history of EU-referenda tells us that the problem for the Remain campaign is that European integration and migration have few enthusiastic supporters but many ardent opponents. It is a duel between technical reasoning and necessity (“We need Europe”), and emotive preferences and attachment (“Us versus Europe”).

British Euroscepticism, like its Danish counterpart, is sovereignty-based. Citizens evaluate the EU based on its perceived interference with treasured national ways of life. If there is interference, cooperation is rejected regardless of possible socio-economic rewards. As in Denmark, a majority dismisses the EU as being undemocratic, but in a “give-us-back-our-powers” way, and certainly not in the manner that democratic Euroscepticism is usually interpreted. Here, in the name of democratisation, powers have steadily shifted from the Council of Ministers to the supranational European Parliament, which is precisely what sovereignty-based sceptics do not want to see.

Denmark’s latest EU-referendum—our seventh—on changing an opt-out on Justice and Home Affairs into a British opt-in model, saw abstract discussions about sovereignty and migration trump specific arguments about police cooperation and corporate competitiveness. Importantly, the Danes understood these latter arguments rather well. Many appreciated that further cooperation could bring about socio-economic benefit. But utility squarely lost when it came down to the vote. To more than two-thirds of no-voters, safeguarding national sovereignty was the winning argument (Just as, by the way, it had been in 2000, when the Danes rejected the Euro, and in 1992, when the Maastricht Treaty was turned down).

Despite decades-long familiarity with Euroscepticism, Danish pro-European politicians failed their campaign. Over the course of a few months their twenty-point lead in the polls vanished. All spoke utility; none spoke sovereignty. Polls suggest that most Danes, concerned mainly about sovereignty, felt unable to explain what the referendum was about, and became more confused by the campaign than they had been before it started. What everyone really wanted to know was how much more “Europe” and “foreigners” a yes-vote would bring about—and not how to get reimbursement for the flawed dishwasher bought from a German online store, or how to obtain more influence in Brussels, as were the oft-cited yes-arguments.

Sovereignty became the no-side’s prerogative, and ultimate triumph. The public thought that the yes-camp was hiding something, and as a result it was always on the defensive. Sovereignty became a much more mysterious issue than a debate about justice cooperation warranted. Why no one turned the argument around (“Is an inelastic block opt-out from all cooperation really the best way to safeguard actual sovereignty?”) is a conundrum.

Sovereignty-based Euroscepticism, when measured through indicators such as opposition to majority voting and to a stronger European Parliament and Court of Justice, is slightly less pronounced in Britain than in Denmark—the European champions in this respect. However, this is “all” there is to Danish Euroscepticism.

Not so in Britain. Here, strong sovereignty-based Euroscepticism couples with widespread economic Euroscepticism—measured through the EU’s perceived inability to improve key sectors or one’s financial situation. To many Brits, membership does not pay. This means that the base for British Euroscepticism is broader and more diverse than in Denmark, where the population highly approves of the EU’s economic impact.

This opens up more attack opportunities for the Leave campaign, where, fittingly, the economy and sovereignty are both core themes. Compared to the Danish no-side, however, it faces the challenge of advocating change, when referendum research suggests that voters are risk-averse and favour the status quo. Whether to terminate a four decade long relationship involves major change, and is a far more sweeping question than any yet submitted to a Danish EU-vote.

Nonetheless, Denmark’s referendum-history offers three pivotal lessons for those engaged in Britain’s vote: