Devolution was always described as a process and not an event. Well, the devolution journey has moved on to a new phase with the May elections in Scotland and Wales, with the result that three nationalist parties now hold power outside England. The SNP win in Scotland was accompanied by a Plaid Cymru win in Wales. Sinn Fein remains the largest party in Northern Ireland with the next elections to the Northern Ireland Assembly due in 2027. So once confirmed in office, John Swinney, Rhun ap Iorwerth, and Michelle O’Neill will represent a triumvirate of nationalist First Ministers. They each lead parties committed to seeking independence from the United Kingdom.
The Celtic alliance
The emerging Celtic alliance between SNP and PC leaders has been kicking around for a while now and is not the sudden post-election initiative many English-centric newspapers would have you believe. Alarmist responses in the press describing ‘quiet Anglophobia’ and the ‘UK under threat’ were predictable. However, the roots of collaboration between the parties can be traced back to a parliamentary agreement between the SNP and PC in 2001. With Sinn Fein becoming the largest party in Northern Ireland, it too has started to tentatively build linkages with the other nationalist parties. The parties share an antipathy towards Westminster, but also a marked pro-EU stance.
Electoral dynamics
Although the three parties share a desire for independence from Westminster, their elections have significant differences. In Scotland, the SNP vote fell but was helped by the split in the unionist vote, with the party emerging as easily the largest in the Scottish Parliament. Without a majority, the SNP will need the support of the pro-independence Scottish Greens.
In Wales the electoral dynamics were very different. Plaid has previously only been a force as a minority party in the Senedd, in coalition with Labour from 2007 until 2011, for example. This election, with a new 96-seat Senedd and a new electoral system, is without doubt the party’s biggest breakthrough. Becoming the largest party may not, though, be a ringing endorsement of Welsh nationalism. Plaid managed to frame the election as a two-horse race between themselves and Reform UK which turned the party into the stop Reform party. Plaid is keen to emulate the SNP in initially demonstrating governing competence, though as the electoral system dictates, this will need to be with the support of the Greens or Labour.
The road to independence
Having nationalist parties governing across the UK is not an immediate threat to the union. In Scotland, John Swinney is keenly aware that without a majority for the SNP he may lack the electoral strength to push for a second referendum. After all, the 2014 referendum was secured after a majority in 2011 and Nicola Sturgeon’s push for a second one post-Brexit faltered without majority support. Swinney is likely to play a longer game.
In Wales the approach is even more cautious, with no commitment to a referendum in the first four years beyond establishing a national commission for Wales – a forerunner to a Wales White Paper. In both Scotland and Wales, the Green parties are pro-independence (a position supported by Zac Polanski), which may prove crucial in government. In Northern Ireland Michelle O’Neill seized on the results to claim that the union was ‘cracking at the seams’. With Sinn Fein facing its own electoral test next May, the party is keen to benefit from nationalist successes, and polls show it as still the largest party even if some of its support has wavered.
Polling in terms of support for independence itself does not present a clear majority in favour in Scotland, Wales or Northern Ireland. In Scotland, though, the pro-independence vote has crept up and polls appear evenly split on the issue. In Wales support for independence has increased to around 33 per cent following the rise of Plaid, the unpopularity of Labour, and the electoral success of the SNP in Scotland. In Northern Ireland support for a united Ireland has grown to over 36 per cent, though has been as high as 41 per cent in favour. Support increases substantially if the question is framed within EU membership.
The constitutional routes
Whether the shifts of the May elections represent a genuine support for independence movements or is more centred on frustration with Westminster and the governing Labour Party is not yet apparent. The rise of a pro-union Reform UK has also created a different kind of electoral foe for the Scottish and Welsh nationalist parties, motivating some of the calls for greater autonomy from the rest of the UK.
However, there are considerable constitutional obstacles to future referenda, regardless of this apparent upswell in support for nationalist parties. In Scotland, the relationship with the pro-independence Scottish Greens may prove crucial in forcing the issue. In 2021 Nicola Sturgeon’s government opted for a formal coalition with the Greens when only one seat short of a majority. The Bute Agreement, which included a commitment to hold a referendum on independence within the parliamentary term fell apart in the wake of the SNP leadership turmoil of 2023. With the Greens holding 15 seats, gaining six in this election, the party now has a stronger hand to play in negotiations, and previous experience in coalition with the SNP may make the party reluctant to formalise an arrangement.
The SNP manifesto pledged to bring forward a vote on an independence referendum in the Scottish Parliament. This was to be tabled on the first sitting day to approve the development of a section 30 order granting Scotland the power to hold an independence referendum. John Swinney is aiming for a 2028 referendum, though without a majority he will need to convince Westminster that any arrangement with the Greens represents a genuine pro-independence majority. We should remember that without Westminster support, Nicola Sturgeon’s attempt to force a referendum in 2022 was blocked by the courts and that the ability to hold a future one remains a reserved matter requiring agreement with the national government.
The route to constitutional independence in Wales is significantly less developed than in Scotland, largely due to a historic ambivalence towards devolution. Plaid Cymru has softened its stance on independence of late, and in its 2026 manifesto, the party did not explicitly set out a timetable for a future referendum, in contrast to the firm commitment in the 2021 manifesto. However, Plaid can now point to the findings of the 2024 cross-party Independent Commission on the Constitutional Future of Wales, which found that independence was a ‘viable option for the future’. Whilst the case is made for greater autonomy, the new Senedd is in a similar situation to Scotland and only able to pass authorising legislation for a referendum with the consent of Westminster.
The route to a border poll is more complicated in Northern Ireland. The Northern Ireland Act 1998 allows for a referendum on Irish unity if it appears likely that a majority of those voting would express a wish that Northern Ireland should cease to be part of the United Kingdom and instead form part of a united Ireland. The Good Friday/Belfast Agreement provides that consent should be freely and concurrently given would suggest that any poll would need to be conducted in Northern Ireland and the Republic at the same time. The exact type of evidence required to demonstrate that majority is uncertain, though any decision would rest with the Secretary of State for Northern Ireland, as Hilary Benn emphasised as recently as October 2025. Prime Minister Keir Starmer’s rare foray into the border poll issue was an ill-judged remark before the 2024 election that he would campaign for the union in any border poll. In practice, though, a border poll would also require consent from the Republic of Ireland, which means three key players would likely need to agree for a referendum to take place.
The politics of the electoral aftermath
All this means is that nationalist parties in power do not automatically translate to a fracturing of the United Kingdom. It does though pose another headache for the UK government. Each nationalist party has an electoral mandate behind them, and a developing Celtic alliance will likely seek to pressure the government to at least devolve greater powers and perhaps give devolved legislatures a greater say in when referenda are called. Mindful that votes for nationalist parties will need to be sustained in a volatile electoral landscape, those leaders will be looking to provide competent governance to gain trust. As part of that, we might expect more assertive testing at the boundaries of nationalist agendas, whilst placing self-determination firmly on the political agenda at Westminster.
Mark Bennister.
Mark Bennister is an experienced academic researching comparative political leadership, prime ministerial power, governance, public policy, and accountability in parliament. He is a Visiting Reader at Queen Mary, University of London, an Affiliate Research Fellow at the Bennett Institute for Public Policy, University of Cambridge, and Honorary Senior Fellow, University of Lincoln.
The Constitution Society is committed to the promotion of informed debate and is politically impartial. Any views expressed in this article are the personal views of the author and not those of The Constitution Society.