IN THE early morning of September 19th Mary Pitcaithly, the person in charge of counting the votes in Scotland’s referendum on independence, declared that the Scots had voted—by 55% to 45%—to stay within the United Kingdom. But with one British constitutional upheaval averted, it took David Cameron, the prime minister, little more than an hour to announce another one. Now that Scotland had decided to stay, with the promise of significantly more leeway to set its own policy, it was time to turn to the question of what to do about England. The prospect of a more powerful Scottish government, said Mr Cameron, meant that the time had come at last to grapple with the West Lothian question, a British constitutional oddity that has kept political scientists and pub bores in happy disagreement for decades. What is it? Although the question dates back to the debates on Home Rule for Ireland in the 1860s (when the entire island was part of the United Kingdom), it was first raised in its modern form in 1977 by Tam Dalyell, then Member of Parliament for the Scottish constituency of West Lothian. He subsequently asked the same question so often that it became known as the West Lothian question. At the time, the UK was pondering whether to establish a devolved Scottish government. That would mean that MPs from England, Wales and Northern Ireland would not vote on certain matters of Scottish policy. But the reverse would not be true: because none of the other nations had a devolved parliament of their own, their affairs would be settled in the UK parliament, where Scottish MPs would still vote even though the policies passed would have no effect in Scotland. When a Scottish parliament (as well as a Welsh one) was finally created in 1999, the question ceased to be theoretical. On two occasions—a vote in 2003 about hospitals, and another in 2004 about university tuition fees—it became very non-theoretical indeed. On both those occasions, votes from Scottish MPs were necessary to push through the bills, even though neither one applied to Scotland.

That is unfair. But, as those constitutional scholars and pub worthies have found, it is far from clear what to do about it. These days England is the only one of the UK's constituent nations without a parliament of its own. One answer would be to set up an English-only chamber, leaving the current UK parliament at Westminster to deal only with trans-Union matters like war, foreign policy, transport and infrastructure. But that is awkward for two reasons. First, the three existing devolved administrations have differing amounts of power, making it unclear what powers the English could expect to receive. Second, a federated UK would be a lopsided beast. England is home to 85% of the country’s population and the lion's share of its economy. England could be chopped up into smaller, more manageable chunks. But whereas Scotland, Wales and Northern Ireland each have a reasonably coherent national identity, the same is not true of England's regions. (One creative proposal is to revive the ancient medieval kingdoms of Wessex, Mercia and the like.) The citizens of the North East were offered a regional parliament in 2004, and voted "no" overwhelmingly.

Britain’s constitution has always displayed a preference for pragmatism and gradualism over logical coherence. With that in mind, other reformers prefer less sweeping solutions. One idea is simply to cut the number of MPs that are sent to Westminster by Scotland, Wales and Northern Ireland. That is a very British proposal: it would not decisively answer the West Lothian question, but it would make it a little less pressing (albeit at the expense of giving the other three nations even less say over UK-wide affairs). Another idea is to forbid non-English MPs from voting on English-only matters (a convention that the Scottish National Party already observes), though critics foresee wrangling over which laws would count. The Economist's preferred solution is "double majority" voting, in which laws that affect England would require approval by both the entire Westminster parliament and, separately, by the English MPs sitting there. Most commentators agree that something, this time, really must change. But they have felt that way before. (Here, for instance, is an article from The Economist in 1997, arguing that the Question had become intolerable.) At the moment, in the febrile aftermath of the UK's near-death experience, things really do feel different. But it is not impossible that The Economist will be writing another explainer on exactly this question in a decade's time.

Dig deeper:

Scotland's place in the UK is settled. Time to deal with its larger neighbour (September 2014)

The referendum in Scotland has opened cracks in the United Kingdom (September 2014)

Mountains, skyscrapers, Oscars, rain: 28 charts show who gets what if Scotland secedes (September 2014)