Boris Johnson Might Break Up the U.K. That’s a Good Thing.

By David Edgerton

The United Kingdom may be finally coming to an end.

On Thursday, Parliament passed the withdrawal agreement on which Prime Minister Boris Johnson successfully campaigned in last month’s general election. By the end of the month, it will be signed into law. The United Kingdom will leave the European Union on Jan. 31.

For decades, membership in the European Union helped glue together a fragmenting United Kingdom; now Brexit is tearing it apart. The short-lived fantasy of the “British nation,” too, may finally meet its end.

Mr. Johnson’s plan is likely to lead to a border between Northern Ireland and Britain for the first time in modern history. The policy — designed to allow Britain to radically break with Europe while Northern Ireland remains aligned with the rest of the bloc, including the Republic of Ireland — is an astonishing betrayal of the Ulster unionists, whose politics is predicated on the sanctity of the United Kingdom. And drawing Northern Ireland into the same regulatory system as its southern neighbor poses a remarkable opportunity for the nationalists. A once-more united Ireland is firmly in view.

That certainly hasn’t gone unnoticed in Scotland. The pro-independence Scottish National Party, which took 48 of Scotland’s 59 seats in December’s election, reads the writing on the wall. A large majority of Scots voted to remain in the European Union during the 2016 referendum; to allow Northern Ireland but not Scotland to remain aligned with the European Union’s market will only add to the sting. Nicola Sturgeon, the S.N.P.’s leader, has already formally requested that the Scottish parliament be given powers to hold an independence referendum. Mr. Johnson, for his part, has made clear that he intends to stand in the way of such a vote, but he may not be able to block it forever.

So maybe this is the end. Not this week, but perhaps by the end of the decade. First Scotland, then Northern Ireland, leaving just England and Wales, a mini-union, which itself could break up under pressure from Welsh nationalists.

Would that really be so bad? Actually, it wouldn’t be. The breakup of the union certainly won’t be easy but it may be one of the few good things to come out of Brexit — not just for Scotland and Ireland but also, and perhaps especially, for England.

After being released from the unionist grip, Northern Ireland could join a flourishing Irish economy and a more socially liberal — how things have changed! — society. For the nationalists it will represent a long-desired reunion. Although Irish unity is what unionists most fear, they might now be able to reconcile themselves to their Irishness after being betrayed by London.

Scotland could take its own future in hand. It has a higher mortality rate than England, and while it is less unequal than its southern neighbor, the gap between them has narrowed over the past two decades. Scots have put off dealing with these issues by putting the blame on London. Independence will deprive them of that excuse and force them to face divisions in their own society. An independent Scotland will come into its own political identity, rather than one premised just on contrasts.

And even England would benefit. Despite its being the dominant nation in the United Kingdom, the arrangement hasn’t been good for it. It doesn’t have a sense of itself as a nation to be transformed and is divided between the vibrant, youthful and pro-European big cities — especially London — and the aging, stagnating and anti-European rest of the country.

Freed from the grip of the decayed British nation and British state, England could finally be done with its delusions of grandeur. Fanciful beliefs about British importance in the world would crumble. England would be only around the eighth-largest economy in the world. And it would probably have to give up its nuclear weapons — the United Kingdom’s nuclear submarine base is in Scotland.

England need not be, as many fear, a rump United Kingdom, parochial, perhaps even irredentist. Less cocksure and more understanding of its real place in the world, it may soon rethink its hostility to the European Union. Scotland suffered a process of deindustrialization similar to northern England’s and Wales’s — but it voted to remain. As the writer Anthony Barnett and others suggest, a progressive English nation, on the model of the Scottish one, could emerge. This England might have an ordinary democratic nationalism that understands its own aspirations and those of others.

The idea of breaking up the union isn’t quite as outrageous as it might seem. The “United Kingdom” is neither ancient nor stable. Before 1945, “national” Irish, Welsh, Scottish and English identities were for many not local varieties of national Britishness but part of something much bigger: an imperial identity.

British World War II propaganda explained that the United Kingdom was just one equal element of a British Commonwealth of Nations that, along with India and the colonies, made up “the British Empire.” It was the empire that fought the war, not the United Kingdom. Soldiers died for “king and country” — but that country had no name. No one died for “the United Kingdom.”

After 1945, “Britain” — a national United Kingdom — was one of many post-imperial constructions that emerged from the ashes of the British Empire. From then into the 1970s, the United Kingdom existed as a coherent economic, political and ideological unit, distinct from the rest of the world. There was a national British economy, a national British Army and a national British politics dominated by two national, unionist parties. It was a brief period of British nationhood. In fact, it was the only one. This national United Kingdom was broken up economically starting in the 1970s by the closely related processes of globalization and deepening economic integration with Europe.

It is this decaying British nationalism, a leftover from the 1970s, that is now disrupting the union, not the self-conscious Scottish, Irish and Welsh versions. Strong in England but weak elsewhere, with the exception of a handful of hard-core unionists in Northern Ireland, this British nationalism manifested itself in the calls for Brexit, from before the 2016 referendum and up to today. The Brexiteers wrongly believe that independence from the European Union will make the United Kingdom great again.

But Brexit and the delusions of the United Kingdom’s grandeur that go with it are the politics of the aged, of those who remember that brief experience of a united, national United Kingdom. The young people of England, like those in the rest of Britain, overwhelmingly supported remaining in the European Union. They also understand we need liberation from the practices of Westminster and Whitehall, not Brussels, and from the self-defeating rage of the old.

Only a few decades ago, a new United Kingdom emerged from the empire. Now, by forcing the breakup of the union, the old — drinking deep the delusions of British nationalism — may make it possible for a new England to emerge from the United Kingdom.

David Edgerton (@DEHEdgerton) is a professor of history at Kings College London and the author, most recently, of “The Rise and Fall of the British Nation: A Twentieth-Century History.”