How borders are drawn and enforced has far-reaching consequences, whether we live on either side of them or halfway across the world.

If the surprise Tory victory in the UK election bolsters the debate about a potential British exit from the European Union, there is going to be at least one member of the opposition with a highly personal stake in the outcome—newly-elected Labour MP Stephen Kinnock is married to Denmark’s prime minister, Helle Thorning-Schmidt.

Thorning-Schmidt is the veteran politician of the two, having led Denmark’s Social Democrats for the last decade and parliament since 2011. This is her husband’s first election after a career as a nonprofit executive. Kinnock, son of the former Labour leader Neil Kinnock, was assigned a fairly safe seat in Wales and won handily, with 49% of the vote.

It’s fairly unusual for the head of government in one country to be married to a lawmaker in another, but Europe’s common market and relatively powerful supranational government have deepened social and economic ties across the continent, especially among the political class.

Kinnock and Thorning-Schmidt have been married since 1996, when the latter was serving on Denmark’s delegation to the European Parliament. As prime minister, she has managed two different coalitions and enacted tax reform. (Globally, she is perhaps best known for taking a selfie with UK prime minister David Cameron and US president Barack Obama at Nelson Mandela’s memorial service.)

Re-elected UK prime minister David Cameron has promised a national referendum on Britain’s continued participation in the EU. This would make an exit by Greece, with its contentious and debt-strained relationship with Europe, seem like a comparatively minor inconvenience.

If the argument against Britain’s exit is that Europe’s social and political ties will outweigh economic strains and nationalist politics, Thorning-Schmidt and Kinnock are a tangible example of the continent’s integration. As is queen Elizabeth II, it should be noted. The UK monarch descends from the German House of Saxe-Coburg-Gotha, part of the UK’s long tradition of importing European royalty to head its monarchy. Elizabeth’s own great-grandmother was a Danish princess.