On 14 September, the leaders of the SNP, Plaid Cymru and Sinn Féin met in Cardiff to sign a Memorandum of Understanding on constitutional change. The document commits the parties to closer cooperation, affirms the right of their respective nations to self-determination and calls on the UK government to “prepare for, plan and facilitate constitutional change in each jurisdiction”.
Three of the four signatories are First Ministers. John Swinney is First Minister of Scotland, Rhun ap Iorwerth is First Minister of Wales and Michelle O’Neill is First Minister of Northern Ireland. The Memorandum presents the simultaneous occupancy of those offices by nationalist or pro-independence politicians as evidence of a changing political landscape.
The signatories nevertheless used their party titles. Swinney signed as Leader of the SNP, ap Iorwerth as Leader of Plaid Cymru, Mary Lou McDonald as President of Sinn Féin and O’Neill as its Vice President. The commitments belong to the parties. They do not purport to bind the Scottish government, Welsh government or Northern Ireland executive.
Their ministerial positions remain essential to understanding the event, though. The agreement draws much of its political importance from the fact that three of its signatories head devolved administrations. The Cardiff Memorandum therefore raises a question about the relationship between the capacity in which a politician acts and the authority which accompanies the public office they hold.
Party office and governmental office
Ministers continue to be party politicians after entering government. Constitutional practice accommodates both roles while requiring a distinction between them.
The Scottish Ministerial Code restricts the use of government facilities and resources for party-political purposes. The Welsh Ministerial Code follows a similar approach and recognises that some overlap between ministerial and party work is inevitable.
The underlying position is reasonably clear. John Swinney does not speak for the Scottish Government when he speaks as SNP leader. Ap Iorwerth cannot commit the Welsh Government simply by signing an agreement while wearing his Plaid Cymru hat.
The Cardiff Memorandum observes that distinction. Its commitments are expressly made by the parties, and the signature block records only party positions. Yet the document itself invokes the three First Ministers as evidence that constitutional change is gathering political support. Their ministerial titles disappear from the signatures while remaining central to the case advanced in the text.
Northern Ireland and the importance of who speaks for whom
The issue is especially sensitive in Northern Ireland.
Ahead of the summit, deputy First Minister Emma Little-Pengelly criticised O’Neill’s participation, saying that O’Neill had neither sought agreement nor permission to attend or sign anything “as First Minister”.
That objection requires some care. O’Neill does not need the deputy First Minister’s permission to attend a party-political summit in her capacity as Sinn Féin Vice President. The relevant issue is whether she claims to represent the Northern Ireland Executive when doing so.
The institutional setting differs from Scotland and Wales. The First Minister and deputy First Minister head a power-sharing executive, and their offices are interdependent. The Northern Ireland Ministerial Code refers expressly to “the joint nature of the offices of First Minister and deputy First Minister”. A number of functions under the Northern Ireland Act 1998 must also be exercised jointly. The difference in titles creates no hierarchy between the two office-holders, however much it might appear otherwise.
O’Neill remains free, as a Sinn Féin politician, to advocate Irish unity and cooperate with other parties seeking constitutional change. Irish unity is not an agreed policy of the Executive, though, and she could not present it as such or unilaterally exercise any function entrusted to the two office-holders jointly. Nothing in the Memorandum itself indicates that she attempted to do so. However, Sinn Féin’s communications surrounding the summit placed her position as First Minister at the centre of its coverage. Her presence allowed the party to point to the changing distribution of political power in Northern Ireland while pursuing its constitutional programme outside the executive.
The institutional rules determine who can speak for the executive and exercise its authority, but they have less purchase over the political status which an office-holder carries into party activity. Public inference, or a failure to appreciate these distinctions, are not accounted for. Whether this speaks to a weakness in the rules or is simply a necessary acknowledgement of the political reality of the situation, can be difficult to judge.
A politics outside intergovernmental relations
The Cardiff summit also occurred beyond the established machinery of intergovernmental relations.
The 2022 review of intergovernmental relations provides the principal framework through which the UK government and devolved administrations manage their relations. Labour’s Council of the Nations and Regions, created in 2024, brings devolved leaders together with the Prime Minister and English regional mayors.
Neither arrangement provided the setting for Cardiff. No UK government representative attended, Little-Pengelly did not participate alongside O’Neill, and the devolved administrations were not required to negotiate an agreed position. The parties were able to discuss constitutional objectives which the devolved legislatures cannot enact unilaterally and which the respective governments could not necessarily endorse together.
Northern Ireland again provides the clearest illustration. Irish unity remains a Sinn Féin objective rather than an agreed policy of the executive. Sinn Féin can still pursue that objective politically with the SNP and Plaid Cymru.
The position in Scotland and Wales is different because their First Ministers lead governments formed by parties which support independence. The Cardiff commitments were nevertheless kept within the parties. They did not become commitments of the Scottish or Welsh governments.
Cross-territorial cooperation between political parties is familiar. The present alignment of party leadership and executive office across the three devolved territories gives it a new character to what has come before. Each party now leads, or plays the leading role in, a devolved government. Their cooperation consequently carries an authority which would be absent if the same agreement had been reached solely among opposition leaders.
This arrangement also permits a form of coordination which the established intergovernmental structures do not readily accommodate. Those structures organise relations among governments and require participants to work within the institutional responsibilities of their administrations. In Northern Ireland, they must also respect the power-sharing character of the executive. The three parties encounter no comparable requirement when formulating a common political position.
Cardiff belongs to an informal layer of territorial politics running alongside the UK’s intergovernmental arrangements. Its participants coordinate as party leaders while drawing political standing from their occupation of governmental office.
Why the boundary matters
There is no constitutional basis for suggesting that the Cardiff signatories acted improperly. Ministers may participate in party activity across the UK, and the use of party titles indicates an awareness of the capacity in which each person attended. Any separate question about public resources would depend on evidence which is not presently available.
The distinction between party and governmental capacity remains important, though, and carries particular weight in Northern Ireland where the allocation of executive authority reflects the requirements of power-sharing. The rules regulate the use of office and prevent abuses of position. However, the point remains that a First Minister attending an event in a party capacity remains publicly recognisable as a First Minister. Some events, and their success, rely upon that fact – the Cardiff summit was one. It is perhaps unsurprising that many are uncomfortable with this situation.
The UK’s territorial constitution is usually examined through its legislatures, executives and intergovernmental institutions. The Cardiff pact illustrates how governing parties can also coordinate constitutional strategy outside those arrangements. Swinney, ap Iorwerth and O’Neill signed in their party capacities, while their parties approached the meeting from positions of executive power across the three devolved territories.
The formal constitution determines who may speak for governments. It cannot confine territorial constitutional politics to the institutions through which those governments conduct their relations. Whether this is the start of the grey area between these expanding remains to be seen.
Darryn Nyatanga.
Dr Darryn Nyatanga is a constitutional law scholar whose research focuses on executive power, devolution, and constitutional change in the United Kingdom. He holds a PhD from the University of Liverpool.
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.