While the UK has chosen Leave in the EU referendum, voters in Northern Ireland and Scotland bucked the overall trend and voted Remain by a margin of 10 per cent greater than their English compatriots. Ominously, such a stark divergence in opinion between the Celtic countries and England means we may have witnessed the first step in the disintegration of the UK as we have known it for over 400 years.

In contrast, in 1975, it was the English who actually voted for the EC by a margin of 10 per cent greater than the Scottish and Northern Irish, who rejected the authority of the London government to act on their behalf, resented yet another foreign government controlling their lives and rebelled at the prospect of heavily-subsidised foreign farmers undercutting domestic farmers. Incredibly, that vote even registered the rare achievement of uniting most Protestants and Catholics in Northern Ireland against membership!

So, what has happened in the meantime to cause this dramatic Celtic transformation?

There are several factors.

First, in 1975, the Northern Irish and Scots saw the EC as a threat to British regional development aid. Back then, the EC had no regional development policy of note. Fast forward to 2016 and the EU now runs a comprehensive regional development fund with deep pockets, investing billions of pounds around the entire island of Ireland and in the most deprived parts of Scotland. Before 2020, Northern Ireland alone was due to get over twice the per capita EU regional development funding of England. Over the same period, Scottish and Irish farmers would have received three times and five times, respectively, the per capita compensation of their English counterparts from the EU’s Common Agricultural Policy (CAP).

Second, since the 1970s, both Scotland and Northern Ireland voters have fought for, and won, limited autonomy, devolution, and their own national parliaments within a more flexible UK structure. Consequently, today, they enjoy a more autonomous and equal relationship with London. Counter intuitively, the EU has actually facilitated this devolution process. Before British membership, devolution provoked fear of disintegration in London. However, within the EU, London recognised that both it and the regions were united within a common European project, making domestic devolution less risky. Moreover, thanks to the EU’s deliberate engagement with regional political parties, both Scottish and Northern Irish parties actually gained political legitimacy and boosted their own local profile. This was an unforeseen positive consequence of membership.

Third, in Northern Ireland, where the Belfast Agreement of 1998 remains the guarantor of the still shaky co-operation between unionist and nationalist communities, shared EU membership of the UK and the Republic played a positive role. As partners in Europe since 1973, the daily and routine contact between Irish and British representatives in a neutral venue helped build the kind of trust lacking for decades and allowed both countries to engage as equal partners. Of course, the massive injection of EU peace-building money into Northern Ireland since 1995, approximately £1.3 billion to date, can only have helped too.

Fourth, the most successful Brexit argument, immigration control, failed to swing the Celtic voters. This is partly because the issue is not as provocative outside of England. Historically, the Scots and Irish have been forced to seek work abroad themselves for so many generations that the word “immigrant” there provokes a much more empathetic response there than it does in England.

Finally, many of the Irish and the Scots voted for the Remain camp on Thursday because, unlike their English counterparts, the present Celtic generation has become fundamentally more comfortable with the notion of belonging to at least two distinguishable cultural or political identities. If you start from the position of willingly accepting that you can be both Scottish and British, then it is not as awkward to add a third tier, European, to this identity mix. Devolution has certainly helped this process. In contrast, English and British identities are often seen as one and the same in England, where the Scottish and Irish notes of the British symphony are often drowned out.

In Northern Ireland, the specific sectarian divide muddies this theory somewhat but dual identity still holds for many there. For the Catholic population, who would reject the British label, this dual identity includes affinity with Catholics in the Irish Republic, a fellow EU member, not to mention the traditional religious link with Rome as an accepted “foreign” authority structure.

Given these transformations in Scotland and Northern Ireland since the 1970s, it is hardly surprising that the Celtic cavalry overturned their 1975 voting deficit with the English on Thursday. However, their ultimate failure to prevent the UK from stumbling over the Brexit cliffs of Dover will make for an awkward and unstable future within the British union.

Peter Moloney is a visiting professor at Boston College history department