Seismic Shift: Nationalist Victories in Celtic Nations Set to Challenge UK's Constitutional Framework
In just four weeks, the political landscape of the United Kingdom is poised for a dramatic transformation. For the first time in history, nationalist parties advocating for the dissolution of the UK are projected to simultaneously govern Scotland, Wales, and Northern Ireland following the elections on 7 May. Angus Robertson, a senior minister in the Scottish government, described this impending change as "seismic", highlighting the profound implications for the union.
Polls Point to a New Political Reality
Consistent opinion polls indicate that after the May elections, England will be bordered by nations led by restless centre-left nationalist parties. Plaid Cymru is expected to take control in Cardiff, the Scottish National Party (SNP) in Edinburgh, and Sinn Féin in Belfast, where it shares power with the Democratic Unionists. This alignment raises the spectre of significant constitutional disputes, potentially plunging Keir Starmer's Labour government in London—or his successor if he is ousted—into turbulent waters.
Sources reveal that all three parties are engaged in discussions to combine forces and challenge the UK government on critical issues such as spending, taxation, welfare, and rejoining the European Union. Concurrently, Starmer may face additional pressure from more English local authorities governed by Reform UK, which champions its own form of British nationalism.
Potential for Open Conflict and Independence Demands
The disputes could escalate into open conflict if the SNP secures an overall majority in May and uses it to demand a second independence referendum, potentially as early as 2028. While some polls suggest this is a realistic prospect, it remains unlikely due to Holyrood's proportional voting system. Robertson emphasised to the Guardian, "It's really important to appreciate that if we are in a situation with three nationalist first ministers out of four nations of the UK, the status quo is not sustainable. There is going to have to be a massive step change in how the UK deals with the other nations of the United Kingdom."
Collaboration and Demands for Greater Autonomy
After decades of collaboration between Plaid Cymru and the SNP at Westminster, Scottish ministers have recently assisted Plaid in preparing for government in Cardiff, sharing tactics and experience gained from 19 years in power in Edinburgh. Rhun ap Iorwerth, the Plaid Cymru leader aiming to end 103 years of Labour dominance in Wales, plans to demand that Starmer grant Wales powers similar to those in Scotland, including devolved policing and justice, control over its seabed, and increased funding.
At Plaid Cymru's autumn conference, ap Iorwerth declared, "The Labour party became so preoccupied with holding on to power that it forgot where it came from and who it was there to serve. We don't have to believe Westminster when they tell Wales 'this is your lot' and that we should be ever grateful for what we're given. We can do things differently. [We] are not here to repair Labour. We are here to replace them."
Shifting Alliances and Constitutional Politics
In a further indication of the UK's evolving constitutional politics, Scotland's First Minister John Swinney has tentatively aligned with Sinn Féin's deputy leader Michelle O'Neill, the First Minister of Northern Ireland's power-sharing government—a previously unthinkable political move. They were pictured together last year at the funeral of Pope Francis at the Vatican, and O'Neill supported Swinney's calls in mid-March for an emergency summit to discuss the energy crisis amid the Iran war.
Expectations are growing that Sinn Féin will leverage potential Plaid Cymru and SNP victories next month to bolster its demands for a poll on Irish reunification by 2030, making this a central issue in its Northern Irish election campaign in May 2027. A senior Labour source noted that centrist politicians in Northern Ireland predict that if Nigel Farage and Reform win the next UK election, support for a border poll and reunification could surge sharply, even within their own ranks.
International Concerns and Expert Analysis
These prospects have unsettled some of the UK's western allies, with diplomats worrying that renewed constitutional conflict could further weaken Starmer's government during a period of global instability. However, other diplomats and experts on British constitutional politics remain more sanguine about the risks to the UK's stability.
Michael Keating, an emeritus and honorary professor at Aberdeen and Edinburgh universities, argued that nationalist victories would present the UK Labour government with a significant test of its maturity rather than immediately threaten the UK's territorial integrity. He pointed out that in other countries, such as Canada and Spain, nationalist parties run regional governments without existentially threatening central governments. "It's high temperature in Spain, but they know what the rules are and they make it work," Keating said. "[This] is normalising devolution; normalising the plurinational state. This is a democratic form of politics."
Brexit's Impact and Labour's Challenges
Keating emphasised that Brexit has intensified the long-running conflict between Whitehall's desire to assert sovereignty through central control and the growing pressure for greater local autonomy in Scotland and Wales after 27 years of devolution. When Britain was in the European Union, all parts of the UK followed the same EU rules, but since Brexit, Whitehall has assumed ultimate control over the devolved nations, much to their frustration.
Starmer came to power in 2024 pledging to heal the deep divisions that marred relations between the Scottish, Welsh, and UK governments under the Tories and to respect the UK's nations and regions. Initially, this closer working relationship with Scotland endured, but under the current Scottish Secretary Douglas Alexander—widely regarded as a hawk on protecting Westminster's interests—relations have deteriorated significantly.
In March, ap Iorwerth brandished a leaked UK cabinet memo in the Senedd in which Starmer implicitly acknowledged Labour could lose in Scotland and Wales but stated the UK should still avoid being "overly deferential" to devolved governments. Starmer wrote, "Each of us will maintain a professional and respectful working relationship with our counterparts in devolved governments." However, he added, "We should be confident in our ability to deliver directly in those nations, including through direct spending, even when devolved governments may oppose this."
Frustrations and Domestic Challenges
Eluned Morgan, Wales's Labour First Minister, has expressed frustration with Labour policy in Westminster, including attempts to cut winter fuel payments and disability benefits. Her colleagues are also angered that Starmer's government has failed to honour manifesto commitments from 2024 to devolve youth justice and probation and has used the post-Brexit internal markets act to impose UK spending on town centre modernisation in Wales, accusing the prime minister of rolling back devolution. A senior Labour source remarked, "Certainly, two years into that administration, there is next to nothing to show on issues which matter to Welsh Labour."
Laura McAllister, a professor of public policy at Cardiff University, noted that collaboration between the three parties at the UK level might not run smoothly, and Plaid Cymru, the SNP, or Sinn Féin may not achieve domestic success. A Plaid Cymru victory in May would be "a pretty revolutionary change" for Wales, but the party must first demonstrate it can govern better than Labour. Since devolution began in 1999, NHS and education standards in Wales have fallen below those in other UK nations, and poverty has deepened.
If Swinney wins in May, he must address a £5 billion spending shortfall; the SNP has retained power by implementing expensive policies without proper budgeting, and public confidence in public services is lower than the 35% support the SNP enjoys in opinion polls. Both parties will likely run minority governments, heavily dependent on deals with other parties that have their own demands.
Sinn Féin's power-sharing government with the DUP is extremely fractious, and public confidence in Stormont and Northern Ireland's ailing public services is waning. There is no certainty their partnership will survive until next year's election or that Sinn Féin's vote will increase.
Policy Divisions and Future Prospects
McAllister highlighted that Plaid Cymru and the SNP are at odds over key policy areas, particularly reforming the Barnett formula—the Treasury system that funds the UK's nations and regions. Plaid Cymru argues that Barnett unfairly penalises Wales, which has the lowest funding per head of the three devolved governments, but the SNP will resist any changes that reduce Scottish spending. "[Ap Iorwerth] knows his first term has to be about showing they can govern effectively, like the SNP did. In Scotland, the terrain and conversation has moved on drastically due to the SNP's electoral successes," McAllister said.
Scottish Labour sources were reluctant to speculate on the challenges posed by nationalist governments across the three devolved nations, with party leaders insisting Labour could still form the next Holyrood government if post-election arithmetic allows. A Scotland Office source stated that UK ministers would prioritise cooperation, saying, "Over the 25 years of devolution, the Scotland Office has, at different stages, been led by different parties and so too has the Scottish government. That is in the very nature of democracy. Whatever the outcome of the election in May—in which not a single vote has yet been cast—the UK government, as it has previously, will continue to engage constructively with the Scottish government to advance the best interests of Scotland within the United Kingdom."
