Scottish Nationalist Party (SNP) leader John Swinney (behind R) walks with Rhun ap Iorwerth (2nd R) of Plaid Cymru in Wales to the parliament building after attending a meeting with the leaders of the main Scottish, Northern Irish and Welsh parties in Cardiff, Wales on September 14, 2026, to press for self-determination votes in their territories. The leaders of the main Scottish, Northern Irish and Welsh parties on September 14 declared their right to "self determination" in a joint agreement signed at a rare meeting in the Welsh capital Cardiff. (Photo by Adrian DENNIS / AFP via Getty Images)

Scottish Nationalist Party (SNP) leader John Swinney (L) speaks as (2nd L to R) Rhun ap Iorwerth of Plaid Cymru in Wales, Mary Lou McDonald, president of Irish Republicans Sinn Fein and Michelle O'Neill, vice president of Irish Republicans Sinn Fein look on, as they attend a meeting in Cardiff, Wales on September 14, 2026, to press for self-determination votes in their territories. The leaders of the main Scottish, Northern Irish and Welsh parties on September 14 declared their right to "self determination" in a joint agreement signed at a rare meeting in the Welsh capital Cardiff. (Photo by Adrian DENNIS / AFP via Getty Images)

(R to L) Michelle O'Neill, vice president of Irish Republicans Sinn Fein, Mary Lou McDonald, president of Irish Republicans Sinn Fein, Rhun ap Iorwerth of Plaid Cymru in Wales and Scottish Nationalist Party (SNP) leader John Swinney speak to the media as they attend a meeting in Cardiff, Wales on September 14, 2026, to press for self-determination votes in their territories. The leaders of the main Scottish, Northern Irish and Welsh parties on September 14 declared their right to "self determination" in a joint agreement signed at a rare meeting in the Welsh capital Cardiff. (Photo by Adrian DENNIS / AFP via Getty Images)

(L to R) Scottish Nationalist Party (SNP) leader John Swinney, Rhun ap Iorwerth of Plaid Cymru in Wales, Mary Lou McDonald, president of Irish Republicans Sinn Fein and Michelle O'Neill, vice president of Irish Republicans Sinn Fein speak to the media as they attend a meeting in Cardiff, Wales on September 14, 2026, to press for self-determination votes in their territories. The leaders of the main Scottish, Welsh and Northern Irish separatist parties were to hold rare talks on September 14 aiming to advance their campaigns to break away from Britain, they announced in a statement. (Photo by Adrian DENNIS / AFP via Getty Images)

Scottish Nationalist Party (SNP) leader John Swinney (L) speaks as (2nd L to R) Rhun ap Iorwerth of Plaid Cymru in Wales, Mary Lou McDonald, president of Irish Republicans Sinn Fein and Michelle O'Neill, vice president of Irish Republicans Sinn Fein look on, as they attend a meeting in Cardiff, Wales on September 14, 2026, to press for self-determination votes in their territories. The leaders of the main Scottish, Welsh and Northern Irish separatist parties were to hold rare talks on September 14 aiming to advance their campaigns to break away from Britain, they announced in a statement. (Photo by Adrian Dennis / AFP via Getty Images)

Rhun ap Iorwerth of Plaid Cymru in Wales attends a press conference with leaders of the main Scottish, Northern Irish and Welsh parties in Cardiff, Wales on September 14, 2026, to press for self-determination votes in their territories. The leaders of the main Scottish, Welsh and Northern Irish separatist parties were to hold rare talks on September 14 aiming to advance their campaigns to break away from Britain, they announced in a statement. (Photo by Adrian Dennis / AFP via Getty Images)

A member (R) of the media adjusts a microphone stand as (L to R) Scottish Nationalist Party (SNP) leader John Swinney, Rhun ap Iorwerth of Plaid Cymru in Wales, Mary Lou McDonald, president of Irish Republicans Sinn Fein and Michelle O'Neill, vice president of Irish Republicans Sinn Fein speak to the media as they attend a meeting in Cardiff, Wales on September 14, 2026, to press for self-determination votes in their territories. The leaders of the main Scottish, Welsh and Northern Irish separatist parties were to hold rare talks on September 14 aiming to advance their campaigns to break away from Britain, they announced in a statement. (Photo by Adrian DENNIS / AFP via Getty Images)

(L to R) Scottish Nationalist Party (SNP) leader John Swinney, Rhun ap Iorwerth of Plaid Cymru in Wales, Mary Lou McDonald, president of Irish Republicans Sinn Fein and Michelle O'Neill, vice president of Irish Republicans Sinn Fein speak to the media as they attend a meeting in Cardiff, Wales on September 14, 2026, to press for self-determination votes in their territories. The leaders of the main Scottish, Welsh and Northern Irish separatist parties were to hold rare talks on September 14 aiming to advance their campaigns to break away from Britain, they announced in a statement. (Photo by Adrian Dennis / AFP via Getty Images)