(Bloomberg) — Boris Johnson’s sweeping election victory is a very English revolution.The prime minister trounced his biggest opponent by luring traditional Labour Party voting heartlands in northern England to his Conservatives for the first time in generations, in some cases ever. Voters clearly rejected Labour leader Jeremy Corbyn’s throwback socialist agenda, but they just as clearly rallied to Johnson’s pledge to “get Brexit done.”At least, they did in England. Scotland and Northern Ireland, both of which opposed leaving the European Union, chose a very different path. In each case, the result is friction with London that looks set to intensify once Brexit happens. That doesn’t bode well for the future of the union, regardless of Johnson’s majority at Westminster.“We are heading towards a new constitutional crisis, which won’t be resolved easily in the next few years,” said Simon Hix, professor of political science at the London School of Economics.Questions over the integrity of the three-centuries-old United Kingdom have been at the forefront of British politics since Scotland’s independence referendum five years ago. It took late intervention from London-based politicians and a raft of new promises for autonomy to avoid the breakup of a nation state that was often heralded as a model of stability. Brexit then upended the concept of union once again. There’s no denying Johnson’s achievement at the ballot box on Thursday in the largest nation in the U.K., but move further to the periphery and it’s a different picture.He successfully extended the Conservatives’ appeal in England across the Brexit-supporting belts of the disaffected—voters identified in surveys as mostly living outside the big cities and who feel ignored by and resentful of their multicultural, cosmopolitan capital. Johnson also did well in Brexit-backing Wales, gaining seats in what was once solid Labour territory to match his party’s performance in 1979.Read More: The End of the United Kingdom May Be NearingIn Scotland, Johnson’s pro-Brexit message was a turn-off to voters who strongly opposed leaving the EU in the 2016 referendum. They’ve never warmed to the prime minister’s bumbling, upper-class Englishman persona, and he hardly featured in Scottish Tory campaign leaflets. Instead, the Scottish National Party increased its dominance.SNP leader Nicola Sturgeon interpreted her party’s thumping win, taking 48 of 59 districts available, as a mandate for a second referendum on independence from the U.K. The last ballot in 2014 was won by the “No” campaign 55% to 45%.Johnson has said he won’t grant the legal power to hold another one. He can continue to do that, but the issue is unlikely to go away. In 2021, Scotland holds its own elections for the semi-autonomous legislature in Edinburgh and the SNP looks set to bolster its hand again.Sturgeon says Brexit turns that stance on its head, and justifies a rerun. For Scottish nationalists, the election results render Johnson’s position untenable. “It is clear that the kind of future desired by the majority in Scotland is different to that chosen by the rest of the U.K.,” Sturgeon said in a televised speech on Friday.In Northern Ireland, pressure looks set to grow for a referendum on unity with the Republic. Nationalists who want to bring the island of Ireland together made advances in the election while unionist parties that want to remain in the U.K. lost their majority.The key here too was Brexit, with Johnson’s deal seen by unionists as weakening ties to Britain. In the most high-profile loss, the Democratic Unionist Party’s deputy leader, Nigel Dodds, succumbed to Sinn Fein in north Belfast. Sinn Fein, formerly the political wing of the Irish Republican Army and the DUP’s most bitter adversary, campaigned under the slogan “Time for Unity.”The Good Friday Agreement, the 1998 accord that largely ended the decades-long violent sectarian conflict in Northern Ireland, states that there can be a vote if the U.K. minister in charge of the province sees a likely majority in favor of a united Ireland.There seems little prospect of a vote anytime soon, as both London and Dublin fear the destabilizing effect such a referendum might have on the region’s peace process. Instead, the focus will likely move to restarting Northern Ireland’s power-sharing assembly, which remains suspended after Sinn Fein brought it down in 2017.“Now is not the time for a border poll,” Ireland’s Europe Minister Helen McEntee said in an RTE radio interview Friday.Read More: Johnson Urges Healing After Winning Election That Upends BritainYet here too, Brexit may alter the dynamics.Bill White, who runs Belfast-based polling company Lucid Talk, said before the election that events in Scotland as well as the impact of leaving the EU will affect sentiment on Irish unification. He sees a border poll as “inevitable,” with any hint of Brexit turmoil meaning “it could be incredibly tight.”Johnson isn’t blind to the cracks appearing in the union, and stressed the need for unity in his victory speech. Neither are the mechanisms for a break-up of the U.K. clear so long as Johnson refuses to play along.What is evident is that Brexit is only now about to happen and the strains are already being felt in Belfast and Edinburgh. The risk for Johnson is that his pursuit of Brexit at the head of a Conservative Party now unbound widens those splits between England and the U.K.’s other constituent nations.To contact the authors of this story: Alan Crawford in Berlin at firstname.lastname@example.orgDara Doyle in Dublin at email@example.comTo contact the editor responsible for this story: Rosalind Mathieson at firstname.lastname@example.org, Rodney JeffersonFor more articles like this, please visit us at bloomberg.com©2019 Bloomberg L.P.