image: maselkoo99, Getty images

In the coming weeks, the Electoral Commission will publish details of how much cash the various larger campaigns threw at the European referendum. The list of big spenders will include some familiar faces: the Conservatives, Labour, the official Leave and Remain initiatives.

But there will be an unlikely name featuring among those big beasts, too: Northern Ireland’s Democratic Unionist party.

Just how much the DUP spent on Brexit remains to be seen. But the Electoral Commission have already let slip something surprising: it’s more than £250,000. And the most obvious reason that a relatively small party had so much to spend on this campaign? Because political donations in Northern Ireland are kept secret.

You might not realise it, but it’s pretty likely you even saw some of the DUP’s Brexit campaign spending. Look closely, for example, at the imprint at the bottom of these placards in Edinburgh in the week of the vote:

Leave campaigners in Edinburgh the day before the vote. 91 Dundela Avenue is the DUP headquarters. Image: Adam Ramsay

It wasn’t just a few stray leaflets or placards that the DUP paid for. On June 21, two days before the vote, the party funded a four-page wraparound pro-Leave advert in the Metro freesheet. While it’s possible to buy such adverts for as few as 10,000 issues of the paper, openDemocracy has spoken to people who saw this propaganda in editions in London, Manchester, Edinburgh, Dundee, Cardiff, and Sunderland. A UK-wide wrap around advert in the Metro costs £250,000: on its own, far more than any Northern Irish Party has ever spent on even the most significant election campaigns.

The one place the advert didn’t appear is the one place the DUP stands for election: Northern Ireland. The Metro doesn’t circulate there. 

“It is safe to assume that this was the most expensive single piece of propaganda ever issued by an Irish political party,” commentator Fintan O’Toole wrote in the Irish Times.