How the UK came together — and potentially apart

The United Kingdom's formation was not a singular event but a progression of unions, legislation, conquests and political settlements that unfolded over several centuries. Recently, however, leaders from the Scottish National Party (SNP), Plaid Cymru, and Sinn Féin signed a memorandum of understanding in Cardiff, prompting a renewed discussion on the UK's potential for constitutional change.

This pact, while significant politically, does not alter the UK's constitutional framework as it is signed by party leaders rather than representatives legally binding their governments. The agreement lacks legal force.

To understand how the United Kingdom came together, we must first consider Wales, which was conquered by the English Crown during the 13th century. The Laws in Wales Acts of 1535 and 1542 formally incorporated Wales into the English legal and political system, granting it representation in England's Parliament. Scotland, on the other hand, took a different path.

Following the death of Elizabeth I in 1603, James VI of Scotland ascended the English throne as James I, thus uniting England and Scotland under a single monarch. However, they remained separate kingdoms with distinct parliaments and legal systems, marking the Union of the Crowns but not yet a political union.

The Union of the Crowns transformed into a political union in 1707 when both the English and Scottish parliaments approved the Acts of Union. Consequently, the Kingdom of Great Britain was formed on May 1, 1707, with a single Parliament. Scotland retained certain unique institutions, such as its separate legal system and church.

Ireland joined the union later, following the 1798 rebellion and fears of French intervention. The Acts of Union, passed by the British and Irish parliaments in 1801, came into effect on January 1, 1801, creating the United Kingdom of Great Britain and Ireland, officially abolishing the Irish Parliament and bestowing 100 MPs from Ireland to Westminster.

Nonetheless, the Irish union was not permanent. The Government of Ireland Act 1920 partitioned the island, establishing separate arrangements for Northern and Southern Ireland. Subsequently, the Anglo-Irish Treaty following the Irish War of Independence led to the creation of the Irish Free State, while Northern Ireland remained part of the UK. This results in the modern United Kingdom being known as the United Kingdom of Great Britain and Northern Ireland.

In 1998, the Good Friday Agreement restored devolved government to Northern Ireland and introduced the Scottish Parliament and Welsh legislature through the Scotland Act and devolution legislation. This agreement also paved the way for the current political landscape in which pro-independence or pro-unification parties lead all three devolved administrations.

However, their objectives differ. The SNP seeks another Scottish independence referendum, Sinn Féin advocates for a referendum on Irish unity under suitable conditions, and Plaid Cymru supports Welsh independence but has not set a specific timeline.

The Cardiff Agreement, a practical cooperation pact between the Scottish and Welsh governments, covers various issues like poverty, living standards, economic growth, climate policy, and international engagement with the EU. However, it does not initiate a process of independence. For Scotland, the biggest obstacle to independence is Westminster.

In 2022, the UK Supreme Court ruled that the Scottish Parliament lacked the authority to hold an independence referendum on its own because the issue pertains to reserved matters, including the Union and the UK Parliament. This hurdle requires Westminster's agreement for a legally authorized referendum, mirroring the situation in 2014 when Scotland voted to remain in the UK (55% to 45%).

Northern Ireland's situation is distinct due to the Good Friday Agreement, which obligates the British government to hold a border poll if the likelihood of Northern Ireland voting to leave the UK and unite with Ireland arises. A comparable vote would also need approval in the Republic of Ireland. Wales, lacking an automatic independence mechanism, would require a political and legal process involving Westminster if it pursued statehood.

Thus, even if nationalist parties win elections, dissolving the UK necessitates referendums, legislation, and negotiations over various assets, debts, borders, pensions, citizenship, trade, defense, and international treaties. The breakup is not solely a matter of constitutional law or flags; it also involves intricate energy considerations.

Scotland generates a significant portion of the UK's renewable electricity, exporting excess power, and independence would introduce complex issues surrounding electricity markets, transmission networks, offshore projects, North Sea resources, and regulatory frameworks.