On Wednesday 23 December, it will be a century since the Government of Ireland Act 1920 (the 1920 Act) became law.

This Insight looks at the Act’s significance for the devolution settlement in Northern Ireland, the creation of a border and the reconstitution of the UK.

Union, devolution and independence

After the Union of 1801, Ireland became a constituent part of the United Kingdom of Great Britain and Ireland. Pressure for Home Rule grew from the late 19th century and after several failed attempts to legislate, Parliament passed the 1920 Act.

This created two devolved legislatures in Ireland, the ‘Parliament of Northern Ireland’ and the ‘Parliament of Southern Ireland’.

Only the Parliament of Northern Ireland was established. Following the Anglo-Irish Treaty of 1921, Southern Ireland instead became the Irish Free State, an independent dominion within the then British Empire.

The commencement of the 1920 Act in Northern Ireland on 3 May 1921 was the first time legislative and executive power had been devolved within the UK.

Northern Ireland’s devolved institutions were based upon a distinctive tripartite division of powers: excepted (the Crown and foreign affairs), reserved (postal services and most taxes) and transferred (everything else).

The Parliament of Northern Ireland

The Parliament of Northern Ireland – known as Stormont – had two chambers, a directly elected House of Commons and an indirectly elected Senate. The monarch was represented by a vice-regal Governor who delegated their executive powers to the Government of Northern Ireland. This was headed by a Prime Minister.

This devolution settlement was contested throughout its existence. There were many allegations of discrimination by the Ulster Unionist Party, which always had a majority in both Houses. Amid a deteriorating security situation, Stormont was abolished by the UK Parliament in 1973.

Today’s unicameral Northern Ireland Assembly represents a deliberate departure from the Parliament of Northern Ireland, although it operates on the same ‘reserved powers model’ as its predecessor. The 1920 Act was repealed on 2 December 1999, the same day powers were transferred to the new Assembly.

Partition and the Northern Ireland border

The 1920 Act also partitioned the island of Ireland. Originally intended as a boundary between two devolved parts of the UK, by the end of 1922 it instead separated two parts of the British Empire. Only in 1949, following the Republic of Ireland’s departure from the Commonwealth, did it become an international boundary.

Initially, the Ireland/Northern Ireland border was defined by reference to certain parliamentary constituencies in the 1920 Act. Maritime boundaries were not considered and remained uncertain until the 1970s.

When the Parliament of Northern Ireland exercised its right (under the 1921 Treaty) to opt out of the Irish Free State, this triggered the formation of a boundary commission to review the existing border.

In November 1925 the commission’s report recommended relatively minor transfers between Northern Ireland and the Free State. But after being leaked to a newspaper the UK, Free State and Northern Ireland governments agreed to suppress the report and confirm the existing border. The commission’s report was not published until 1969.

By 1923 the border had become a customs frontier, while in 1969 it was also securitised at the beginning of The Troubles. The creation of a European Single Market in the late 1980s removed the border’s customs elements, while under the 1998 Belfast/Good Friday Agreement the UK government committed to dismantle its security installations.

Creation of the United Kingdom of Great Britain and Northern Ireland

Settlement of the border issue in 1925 led to consideration of how the British monarch and UK Parliament ought to be styled. The then King’s title was George V of “the United Kingdom of Great Britain and Ireland”. This would have remained unchanged had the 1920 Act taken full effect.

But at the 1926 Imperial Conference it was agreed this “hardly accorded with the altered state of affairs arising from the establishment of the Irish Free State as a Dominion.” Accepting a suggestion from Kevin O’Higgins, the Free State’s Minister for External Affairs, the wording was changed to “of Great Britain, Ireland and the British Dominions beyond the Seas”.

This became known as ‘O’Higgins’s comma’. The UK government explained that it treated Ireland “not as a political entity, but as a geographical entity”.

The Royal and Parliamentary Titles Act 1927 received Royal Assent on 12 April 1927. This:

  • authorised the King to issue a royal proclamation within six months to alter the royal style and titles;
  • changed the UK legislature’s name to the Parliament of the United Kingdom of Great Britain and Northern Ireland;
  • meant the term ‘United Kingdom’ would refer, in every Act and public document produced thereafter, to Great Britain and Northern Ireland.

A royal proclamation was issued on 13 May 1927. As the Secretary of State for Northern Ireland, Brandon Lewis, said at the launch of events intended to mark the centenary of Northern Ireland:

2021 marks 100 years since the creation of Northern Ireland, which paved the way for the formation of the United Kingdom as we know it today.

Further reading

Parliament and Northern Ireland, 1921-2021, House of Commons Library.

Government of Ireland Act 1920: What system did it create?, House of Lords Library.


About the author: David Torrance is a researcher at the House of Commons Library, specialising in devolution and the constitution.

Image: George V opening the Parliament of Northern Ireland on 22 June 1921 (reproduced with the permission of the Northern Ireland Assembly Commission).