Scotland's First Minister John Swinney has predicted that Andy Burnham will be “the last prime minister of the United Kingdom”, dramatically escalating the constitutional row following a landmark meeting of nationalist leaders in Cardiff.
The SNP leader made the claim after signing an agreement with Plaid Cymru and Sinn Féin calling on the UK Government to prepare for and facilitate constitutional change across Scotland, Wales and Northern Ireland.
Swinney argued that Burnham's own comments in the House of Commons last week had effectively acknowledged the principle that Scotland should be able to hold another independence referendum if public opinion moves decisively in favour of one.
Downing Street has rejected that interpretation and insisted that the Prime Minister remains strongly committed to the Union and does not intend to engage in further referendums.
Swinney: Burnham will be the last UK prime minister
Speaking in Cardiff, Swinney said a hallmark of Burnham's political approach was the belief that decisions should be taken as close as possible to the people affected by them.
He argued that following that principle logically meant recognising the right of people in Scotland to decide their own constitutional future.
Swinney said Burnham's comments at Prime Minister's Questions were therefore “the absolutely crucial point”, adding that this was why he believed Burnham would be “the last prime minister of the United Kingdom”.
The First Minister went on to predict that, if Scots were given another referendum on independence, they would vote to leave the United Kingdom.
That is Swinney's political prediction rather than an established constitutional outcome. No second Scottish independence referendum has been authorised by the UK Government.
Burnham's Commons comments triggered row
The dispute stems from comments Burnham made in the House of Commons while answering a question about Scotland's constitutional future.
Referring to the mechanism for a border poll in Northern Ireland, Burnham said such a vote should be considered when there was a clear consensus and public opinion had changed sufficiently for the question to require consideration.
He then said it was “exactly the same situation in Scotland”.
Swinney immediately seized on the remark, arguing that the Prime Minister had accepted the principle that majority support for Scottish independence should lead to another referendum.
On 10 September, the First Minister wrote to Burnham inviting him to meet and discuss how that principle could be converted into an agreed legal mechanism.
However, Burnham subsequently wrote to Swinney saying he had simply been highlighting that there was currently no consensus for another independence referendum in Scotland.
Downing Street insists Burnham believes strongly in Union
Downing Street has now pushed back against Swinney's interpretation of the Prime Minister's position.
Burnham's official spokesperson said the Prime Minister was committed to delivering change across all four nations of the United Kingdom and “believes strongly in the union”.
No 10 said the Government would focus on easing pressure on household finances and delivering greater economic security rather than engaging in constitutional debates or further referendums.
That means there remains a fundamental disagreement between the UK and Scottish governments over what Burnham's Commons remarks actually mean in practice.
Comments follow Cardiff nationalist agreement
Swinney made his prediction after the SNP, Plaid Cymru and Sinn Féin signed a memorandum declaring that “Westminster's time is coming to an end”.
The parties said each nation had the right to determine its own future democratically and called on the UK Government to “prepare for, plan and facilitate constitutional change”.
The three parties have different constitutional objectives. The SNP campaigns for an independent Scotland, Plaid Cymru supports Welsh independence and Sinn Féin seeks Irish reunification.
The political agreement does not itself create any new referendum mechanism or alter the constitutional status of any part of the United Kingdom.
Separate Scottish and Welsh government agreement signed
In a separate development on Monday, Swinney and Welsh First Minister Rhun ap Iorwerth also signed the Cardiff Agreement between the Scottish and Welsh governments.
That government-to-government agreement covers cooperation on areas including child poverty, the cost of living, economic growth, climate change and international engagement.
It also records the two administrations' shared belief that people in Scotland and Wales should be able to determine their own constitutional futures.
This is distinct from the party-political memorandum involving the SNP, Plaid Cymru and Sinn Féin.
Swinney wants referendum during current Holyrood term
Swinney has said he wants Scotland to be given a choice on its constitutional future during the current Scottish Parliament term, which runs until 2031.
The Scottish Government published a draft Independence Referendum Bill in August, but Holyrood cannot unilaterally legislate for an independence referendum outside its devolved competence following the Supreme Court's 2022 ruling.
A lawful referendum of the type sought by the Scottish Government would therefore require a route agreed with Westminster or a change in the existing legal position.
Burnham's remarks have consequently become politically significant because the SNP believes they provide an opening to argue for such a mechanism.
Downing Street's response makes clear that the UK Government does not accept that Burnham has committed himself to providing one.
Battle over future of Union intensifies
Swinney's declaration that Burnham could be the final UK prime minister is among his strongest statements since winning a fifth SNP term in government.
But it remains a political forecast. Scotland remains part of the United Kingdom, there is no authorised independence referendum and the UK Government continues to state its support for the Union.
The immediate political battle is therefore over whether Burnham's comments have changed the terms of the independence debate — and whether the Prime Minister can continue to resist a referendum if sustained majority support for independence emerges.
Sources
- Scottish Government: First Minister writes to Prime Minister on Scotland's right to decide — 10 September 2026
- Scottish Government: Cardiff Agreement signed — 14 September 2026
- Holyrood: John Swinney says Andy Burnham will be last UK prime minister — 14 September 2026
- RTÉ: Burnham will be last Prime Minister of UK, says Swinney — 14 September 2026