On 14 September 2026, the First Minister, John Swinney MSP, met the First Minister of Wales, Rhun ap Iorwerth MS, in Cardiff. The two leaders signed the ‘Cardiff Agreement’, a framework for collaboration between the Scottish and Welsh Governments.
This blog outlines what the Agreement covers and how it relates to broader intergovernmental relations in the UK.
Context
Following the May 2026 Senedd elections, Plaid Cymru formed a minority government and Rhun ap Iorwerth took office as First Minister of Wales.
Together with Sinn Féin’s Michelle O’Neill MLA (who has served as First Minister in the Northern Ireland Executive since 2024), this has meant that, since May 2026, the three devolved governments in the UK are all led by First Ministers from parties who favour leaving the UK (though the Democratic Unionist Party’s Emma Little Pengelly MLA also serves in the co-equal role of Deputy First Minister in Northern Ireland).
SNP, Plaid Cymru & Sinn Féin summit
On the same day as the Cardiff Agreement was signed, John Swinney, Rhun ap Iorwerth, Michelle O’Neill, and Sinn Féin President Mary Lou MacDonald met as representatives of their political parties. They agreed a Memorandum of Understanding, which was separate from the Cardiff Agreement.
The full text of the Memorandum is available online. It declares that “each of our nations has the right to determine its own future, through democratic means and in accordance with the wishes of its people” – while also stating that each nation will do so “in its own way and in its own time”. It commits to “strengthening cooperation” between the SNP, Plaid Cymru and Sinn Féin, and calls for the UK Government to “plan and facilitate constitutional change in each jurisdiction”.
Unlike the Memorandum, the Cardiff Agreement is an agreement between the Scottish and Welsh Governments (as opposed to the leaders’ political parties).
What’s in the Cardiff Agreement?
In a letter to the Convener of the Europe, External Affairs and Culture (EEAC) Committee dated 14 September 2026, the First Minister described the Cardiff Agreement as a “bilateral framework […] setting out areas of shared interest and cooperation between the Scottish and Welsh Governments”, with the aim of improving outcomes for the people of Scotland and Wales.
The Foreword to the Agreement observes that:
For the first time since the advent of devolution, Scotland and Wales are led by governments who believe in the potential we have to thrive as independent nations. Whilst Scotland and Wales are on different constitutional journeys, we are bound by a trust in our people’s ability to decide their future for themselves.
The Agreement is not legally binding and does not affect the powers or responsibilities of either government. A Welsh Government written statement said that the Agreement respects the “distinct democratic mandates, priorities and accountabilities of both governments”, and that each government will “continue to determine its own policies”.
Areas of cooperation
The Agreement identifies various policy areas where it says that the two Governments will work together, including:
- tackling child poverty
- addressing cost of living pressures
- promoting sustainable and inclusive economic growth
- tackling climate change
- international activity, including “maximising the opportunities and benefits of our relationships with the European Union and other international partners”, and
- “recognising the importance of language, culture, media and sport in expressing national identity, supporting communities and enhancing wellbeing”.
This list is not exhaustive, and these areas can be reviewed by mutual agreement.
Constitutional arrangements
The Foreword to the Agreement states:
The United Kingdom in its current form is unjust and unsustainable. We will use every opportunity available to us to press the case for greater fairness for Wales and Scotland in areas such as the operation of the UK funding arrangements and powers over our constitutional future.
The Agreement itself says that the two Governments will jointly:
- consider issues affecting the operation of devolution in Scotland and Wales, including the UK Internal Market Act and the Sewel Convention
- collaborate on the operation of legislative consent processes for UK legislation
- promote, and share learning on, mechanisms for public participation and measures to strengthen public trust in democratic institutions, and
- support opportunities to strengthen devolved governments’ roles within UK governance arrangements.
Ways of working
The Agreement sets out different ways in which the two Governments might work together, including:
- sharing evidence, expertise and best practice
- collaborating on joint research and policy development where appropriate, and
- exchanging information on emerging policies and legislative proposals.
The two Governments will “seek opportunities to develop common approaches where interests align”. However, the Agreement also makes clear that this will not necessarily result in policy alignment, and that the two Governments “remain free to pursue different approaches”.
The two Governments will also “collaborate more broadly with other governments on common interests, including engagement with the UK Government and the Northern Ireland Executive where appropriate”.
How does the Agreement fit with other intergovernmental activity?
The Agreement is not part of the UK’s formal intergovernmental relations structures, as established in January 2022. While those structures govern interactions on a four-nations basis between the UK Government and the devolved governments, the Agreement is a bilateral arrangement between the Scottish and Welsh Governments, and their interactions under the Agreement will sit alongside the UK-wide structures.
SPICe has published an explainer on intergovernmental activity and its implications for the Scottish Parliament.
Another SPICe explainer, ‘How Devolution Works’ (published in May 2026), notes that:
One of the main challenges in understanding how intergovernmental activity is shaping policy development and legislation is a lack of transparency in intergovernmental processes.
During its inquiry into the transparency of intergovernmental activity and its implications for parliamentary scrutiny, the Session 6 Constitution, Europe, External Affairs and Culture Committee heard concerns about the consistency and adequacy of Ministerial reporting to parliamentary committees on intergovernmental meetings held outside the formal intergovernmental relations structures.
The Cardiff Agreement states that the Scottish and Welsh Governments “recognise the important scrutiny role of Senedd Cymru and the Scottish Parliament”, and that intergovernmental engagement under the terms of the Agreement “will be subject to existing accountability and scrutiny arrangements”.
How significant is the Agreement and what comes next?
Quoted in a Scottish Government news article, John Swinney said the Agreement was “an important moment in the history of devolution” and marked a “new era of co-operation” between the Scottish and Welsh Governments.
At this early stage, it is difficult to judge what effect the Agreement may have on relations and cooperation between the Scottish and Welsh Governments. Its impact on the wider UK intergovernmental relations landscape also remains to be seen. It will be challenging for the Parliament to come to an informed view of the significance of the Agreement if concerns about a lack of transparency in informal and bilateral intergovernmental activity are not addressed.
The Agreement states that the two First Ministers will meet “at least annually” to review progress, consider emerging opportunities for further collaboration, and agree future priorities. It also states that other relevant Ministers and officials will meet “regularly” to advance cooperation across agreed policy areas.
John Swinney MSP and Rhun ap Iorwerth MS are due to meet again – together with Prime Minister Andy Burnham MP and Michelle O’Neill MLA – at a meeting of the UK Government’s National Economic Council in October. The Scottish Government is also due to host a meeting of the Interministerial Standing Committee (part of the UK’s formal intergovernmental relations structure) this autumn, which will be chaired by Deputy First Minister, Jenny Gilruth MSP.
Duncan Sim, Senior Researcher (Devolution, Constitution and Parliament)