Londonderry City was a parliamentary constituency in Ireland, representing the city of Derry in County Londonderry. It returned one Member of Parliament (MP) to the United Kingdom House of Commons on the electoral system of the first past the post.
The parliamentary borough of Londonderry was granted representation in the House of Commons of the United Kingdom under the Acts of Union 1800 which took effect on 1 January 1801. It inherited the boundaries and franchise of the Londonderry City constituency of the abolished Irish House of Commons.
A report on the constituency was conducted in December 1831, proposing a new boundary. The Parliamentary Boundaries (Ireland) Act 1832 defined the boundaries of the parliamentary borough as:
Under the Representation of the People (Ireland) Act 1868, its boundaries were extended to include all of the municipal borough of Londonderry. It was not affected by the Redistribution of Seats Act 1885 or the Redistribution of Seats (Ireland) Act 1918.
The Government of Ireland Act 1920 established the Parliament of Northern Ireland, which came into operation in 1921. The representation of Northern Ireland in the Parliament of the United Kingdom was reduced from 30 MPs to 13 MPs, taking effect at the 1922 United Kingdom general election. Londonderry City, North Londonderry and South Londonderry were combined to form the single-seat county constituency of Londonderry.
After the extension of the franchise under the Representation of the People Act 1884, the constituency was one of the most marginal seats in Ireland.
Sinn Féin won in 1918. The MP, Professor Eoin MacNeill, was also returned for National University of Ireland. As MacNeill did not take his seat in the United Kingdom House of Commons he could not choose which constituency he would represent and arrange a by-election in the other. He played an active role in the First Dáil and in the Ministry of Dáil ÃÂireann.
The elections in this constituency were conducted on the electoral system of first past the post.
On petition, Ferguson's election was declared void, causing a by-election.
Ferguson's death caused a by-election.
Dowse was appointed Solicitor-General for Ireland, requiring a by-election.
Dowse resigned after being appointed Chief Baron of the Irish Exchequer, causing a by-election.
On petition, Lewis was unseated. McCarthy was named as MP on 25 October.
Knox resigns, triggering a by-election.
Hamilton is appointed Treasurer of the Household, prompting a by-election in which he stood unopposed.
Hamilton becomes Duke of Abercorn, prompting a by-election.
Hogg's death prompts another by-election.