Scotland, Wales and Northern Ireland are demanding greater control over their futures. But if the Union breaks apart, what would independence actually mean?
Oliver Grant
John Swinney’s suggestion that Andy Burnham could be the last Prime Minister of the United Kingdom was deliberately provocative. But behind the rhetoric lies a serious constitutional question: how much longer can Westminster remain the final authority over the political futures of all four nations?
On 14 September, leaders of the SNP, Plaid Cymru and Sinn Féin met in Cardiff and signed a memorandum calling for the British Government to prepare for constitutional change. The agreement asserts the right of Scotland, Wales and Northern Ireland to determine their own futures through democratic means.
The three parties do not seek exactly the same outcome. The SNP wants Scottish independence, Plaid Cymru supports Welsh independence, while Sinn Féin seeks Irish reunification. The memorandum itself recognises those differences and says each nation will determine its future in its own way and in its own time.
So this is not a single independence movement. It is a new level of political coordination around a common argument: that constitutional decisions should not be determined by Westminster alone.
Three different constitutional questions
Northern Ireland has the clearest legal route to constitutional change.
Under the 1998 Belfast Agreement, a border poll can be called when the UK Secretary of State considers it likely that a majority would vote for Irish reunification. That does not mean a poll is imminent, but it gives Northern Ireland a constitutional mechanism that does not exist in the same form in Scotland or Wales.
The economic consequences would be substantial.
Official figures show that Northern Ireland businesses sold £20.1 billion of goods and services to Great Britain in 2024, while exports to Ireland reached £10.5 billion. Ireland was Northern Ireland’s largest export market outside the UK.
Any move towards reunification would therefore involve difficult negotiations over trade, taxation, healthcare, pensions, public spending, citizenship and the future operation of the border.
Scotland faces a different constitutional problem.
Scotland voted against independence in 2014. Two years later, it voted strongly to remain in the European Union while the UK as a whole voted to leave.
The SNP argues that Brexit changed the circumstances surrounding the 2014 referendum. Westminster has not accepted that as a basis for another vote.
The legal position is clearer. In 2022, the UK Supreme Court ruled that the Scottish Parliament cannot legislate for an independence referendum on its own because the Union and the UK Parliament are reserved matters.
That leaves Scotland with a continuing political demand for another referendum, but without a unilateral legal route to hold one.
Wales is further from independence.
Plaid Cymru’s participation in the Cardiff memorandum places Welsh constitutional aspirations alongside those of Scotland and Northern Ireland. But the Welsh case remains different, with public support for independence lower than in Scotland and the constitutional debate also focused on greater devolution and economic powers.
What would independence actually mean?
The political argument often stops at sovereignty. The practical argument begins there.
An independent Scotland would have to negotiate arrangements covering currency, public debt, pensions, defence, international representation, trade and regulation.
Wales would face the additional task of creating or assuming many state functions currently exercised through UK institutions.
Northern Ireland would face a different settlement altogether because reunification would involve the constitutional relationship between the United Kingdom and the Republic of Ireland.
England would also be transformed.
If one or more nations left the United Kingdom, Westminster would have to reconsider the UK’s fiscal system, defence arrangements, international representation, public institutions and internal market.
The breakup of the Union would therefore not simply create smaller countries. It would require the redistribution or reconstruction of institutions that currently operate across the United Kingdom.
Pressure, not collapse
The Cardiff agreement should not be presented as evidence that the United Kingdom is about to disappear.
The constitutional objectives, legal routes and levels of public support are different in Scotland, Wales and Northern Ireland. The memorandum itself acknowledges that each nation will determine its future separately.
But the political landscape has changed.
For the first time, pro independence parties leading the governments of Scotland, Wales and Northern Ireland have publicly joined forces around a common demand for greater control over their constitutional futures.
That creates a new challenge for Westminster.
The question is increasingly not simply whether constitutional pressure exists, but how the British Government responds to demands for greater autonomy while maintaining a functioning United Kingdom.
The real question for Burnham
Could Andy Burnham become the last Prime Minister of the United Kingdom?
There is no evidence today that this outcome is inevitable.
But Swinney’s warning exposes a deeper constitutional dilemma.
Scotland, Wales and Northern Ireland are increasingly demanding greater control over their political futures, while the practical costs and consequences of separation remain unresolved.
The United Kingdom has survived wars, economic crises and major constitutional reforms.
Its next challenge may be more fundamental.
The question is no longer simply whether Britain can remain together.
It is whether the four nations can agree on what being together should actually mean.
Oliver Grant is a British journalist based in London, known for his calm insight, clear storytelling and thoughtful approach to social affairs, politics and culture. His work combines investigative depth with human-centred reporting, exploring the issues that shape communities and public life. Through digital and broadcast platforms, Oliver brings a balanced perspective to complex subjects, championing journalism that informs, challenges and encourages meaningful conversations.*
