Scottish, Welsh and Northern Irish Nationalist Leaders Unite Over Right to Independence

The leaders of Scotland's, Wales's and Northern Ireland's main nationalist parties have gathered in Cardiff to sign a joint declaration asserting their nations' right to self-determination, marking one of the most significant displays of cross-border nationalist solidarity in years. The meeting, held overnight, brought together Scottish National Party leader John Swinney, Plaid Cymru leader Rhun ap Iorwerth and Sinn Féin's Mary Lou McDonald and deputy leader Michelle O'Neill to announce a formal memorandum of understanding.

The rare summit in the Welsh capital came just days after US President Donald Trump publicly expressed support for a united Ireland — comments O'Neill said demonstrated that "the unity debate is very much alive."

What the Agreement Says

The memorandum of understanding signed by the four leaders is built around a central principle: that Westminster has no authority to override the democratic will of each nation. "Our nations have the right to self-determination. No Westminster government has the right to block democracy or undermine the principle that our people will decide their own future," the agreement stated.

The document also noted that, for the first time, each nation had a first minister "committed to independence from the UK," and declared that the future of all three nations "belongs in the European Union." The leaders met in their capacities as party leaders rather than as heads of their respective devolved governments — a distinction that underscores the political, rather than governmental, nature of the declaration.

The three parties are now the largest in their respective legislatures. The SNP and Plaid Cymru hold that status in the Scottish and Welsh parliaments for the first time since devolution began in 1999, while Sinn Féin has been the biggest party in Northern Ireland's assembly since 2022.

Different Timelines, One Broad Term

Despite their shared ambitions, the three parties are pursuing independence — or reunification — under very different conditions and timeframes. The SNP is pushing for a second Scottish independence referendum following the 2014 ballot, in which Scotland narrowly voted to remain within the United Kingdom. Successive UK governments have rejected holding an immediate rerun.

Sinn Féin, the party that was once the political wing of the paramilitary Irish Republican Army, is campaigning for a referendum on reunifying Northern Ireland with the Republic of Ireland. Under the 1998 Good Friday Agreement — the accord that largely ended three decades of conflict — such a vote can be triggered if Westminster's Northern Ireland minister determines that a majority of people in the territory would likely back unification.

Plaid Cymru's position is more cautious. Iorwerth has explicitly ruled out pressing for a Welsh independence referendum during the current term, with the party having won its recent election campaign by deliberately steering clear of the issue.

Cardiff University politics professor Laura McAllister explained that the broad language of "self-determination" used throughout the agreement was a deliberate choice, designed to accommodate these differing goals and timelines rather than forcing the parties into a single, uniform position.

UK Government Pushes Back

The agreement places the three nationalist parties on a direct collision course with UK Prime Minister Andy Burnham's government. Shortly after taking office, Burnham declared that a referendum on Irish unity was "off the table" — a position Sinn Féin leader McDonald flatly rejected, arguing that the prime minister had no authority to override provisions of the Good Friday Agreement.

Burnham subsequently walked back some of his language in parliament, though a spokesperson maintained that the prime minister "believes strongly in the Union" — the constitutional arrangement that keeps Northern Ireland within the UK.

On the question of Scottish independence, Burnham told lawmakers that another vote could occur if there was a "clear consensus," though his government has not defined what that threshold would look like in practice.

What Comes Next

The Cardiff summit represents a symbolic escalation by nationalist parties who collectively govern more territory and represent more voters than at any point since devolution began. Trump's intervention on Irish unity added an unexpected international dimension to the debate, lending the issue fresh momentum ahead of what could be a prolonged political contest with London.

With all three parties now bound by a formal memorandum and united around the language of self-determination, pressure on Westminster to engage more substantively with the independence question — rather than dismiss it — looks set to intensify in the months ahead.