Celtic nationalists unite on independence push as Westminster faces pressure

For the first time in modern British politics, three centre-left nationalist parties that openly aspire to leave the United Kingdom now hold power simultaneously in Wales, Scotland, and Northern Ireland. That shift began in May. This week, it became official.

In Cardiff on Monday, the leaders of these parties gathered to sign a memorandum of understanding. Rhun ap Iorwerth of Plaid Cymru, John Swinney of the Scottish National Party, and Michelle O'Neill of Sinn Féin—who shares executive power with the Democratic Unionist Party in Northern Ireland—sat together with Mary Lou McDonald, leader of the opposition in the Republic of Ireland. They affirmed their nations' right to seek independence and called on Westminster to "prepare, plan and facilitate constitutional change" in all three territories. The statement declared that no Westminster government has the right to block a referendum should the public demand one.

The timing was deliberate. Plaid Cymru had just ended a century of Labour control of the Welsh parliament in May elections. The SNP secured an unprecedented fifth consecutive term at Holyrood, though with a notably muted campaign. Sinn Féin, despite slipping in popularity, remains the largest party in Northern Ireland's power-sharing government. Together, they represent a political realignment that Westminster cannot ignore—even as Prime Minister Andy Burnham struggles to articulate a coherent response.

Yet the agreement masks significant differences in strategy and urgency. At the Cardiff press conference, Swinney and O'Neill called for immediate independence referendums in Scotland and Northern Ireland. Ap Iorwerth, by contrast, declined to set a timetable for Wales, signaling that Plaid Cymru intends to focus on domestic governance first. Current polling shows 32 percent of Welsh voters support independence, a figure that is growing but remains lower than in Scotland, where support hovers near 50 percent. In Northern Ireland, 36 percent back Irish unity—a figure that has not shifted decisively since Brexit, despite predictions to the contrary.

The agreement also arrives amid considerable domestic pressure on each party. The SNP is reeling from the jailing of former chief executive Peter Murrell for embezzling party funds. Scotland's international education rankings have slumped. The government faces a projected budget shortfall of nearly five billion pounds by the end of the decade. For Sinn Féin, public services are crumbling and key infrastructure pledges remain unfulfilled. In Wales, Plaid Cymru must navigate a Senedd in which Reform UK holds more than a third of seats—a complication mirrored in Scotland, where Reform is joint second-largest party alongside Labour. Both nationalist leaders have benefited electorally from opposition to right-wing populism, but governing alongside it presents a different challenge.

Burnham finds himself in a philosophical bind. His government has already rejected SNP proposals for a Scottish work visa to address migrant worker shortages. Wales is pressing for devolution of justice powers. Some Labour figures have suggested devolving authority to regional bodies rather than the national parliaments—a move that would effectively sidestep the institutions now seen as "captured" by nationalists. Yet Burnham has not clearly articulated what he means by devolution at the national level versus the regional level, or how his government intends to manage the fundamental tension: an architecture of devolution already exists in these nations, and it is now competing directly with Westminster for control.

The Cardiff meeting gained unexpected weight from unscripted interventions. Donald Trump told reporters during a visit to Ireland that he would "love" to see a united Ireland and it "may as well happen now"—a comment that drew swift rebuttal from unionists and the UK government, though SDLP leader Claire Hanna offered a characteristically sharp response. Weeks earlier, Burnham had declared a reunification referendum "off the table," forgetting that the Good Friday Agreement includes a provision for a border poll should a majority of Northern Irish voters appear to want it. At Prime Minister's Questions, he suggested a second Scottish independence referendum could be held if a "clear consensus" emerged, then immediately walked it back, telling Swinney such a vote was "off-limits."

What happens next remains uncertain. The nationalist leaders are clearly thinking in longer arcs. Bethan McKernan, The Guardian's Wales correspondent, observed that "there is this sense that since Plaid Cymru won the Senedd elections in Wales in May, this is a new chapter in the Celtic struggle for independence." Plaid Cymru is already learning from SNP successes, launching a child poverty payment modeled on Scotland's. The SNP, facing domestic travails, has an opportunity to refocus the conversation on independence and confront London. Sinn Féin is eyeing next year's Stormont elections, where it is likely to gain ground against a fragmented unionist opposition. None of this guarantees movement toward actual referendums or constitutional change. But the architecture is now in place, the pressure is mounting, and Burnham has yet to offer a coherent answer to the question these three parties are posing: what does the United Kingdom actually look like when its constituent nations no longer wish to be constituent parts?