This Commons Library briefing paper provides brief details of the different voting systems currently used in the United Kingdom. It also notes recent developments relating to voting systems in the UK and provides information about previous government reviews into voting systems. The final section gives details of the voting systems used in selected overseas countries.Jump to full report >>
Before 1997 all elections in the UK, with the exception of Northern Ireland, used the same voting system. However, since 1997 a number of different voting systems have come to be used.
There is a Table in the associated PDF shows where the voting systems are used in the UK.
First past the post is the current system for electing MPs to the House of Commons. The UK is divided into 650 separate constituencies, each of which elects a single Member of Parliament. Winning candidates must receive more votes than any other candidate; they do not need a majority of all votes cast in order to be elected.
First past the post is also used for local elections in England and Wales.
Under the AV system, voters are entitled to rank candidates in their order of preference, marking 1, 2, 3 etc against the candidates’ names on the ballot paper. If a candidate receives more than 50 per cent of the first preference votes then they are elected.
If no candidate reaches the 50 per cent threshold then the candidate with the fewest first preference votes is eliminated and their second preference votes are reallocated to the remaining candidates.
The supplementary vote system is similar to AV. Under the supplementary vote, there are two columns on the ballot paper.
Voters mark an X in the first column against the name of their first choice candidate and an X in the second column indicating their second preference (although they are not required to so so). Unlike under AV, voters are limited to making only a first and second choice.
If a candidate receives more than 50 per cent of the first preference votes then they are elected. If no candidate reaches a majority at the first stage then all but the two candidates with the most votes are eliminated simultaneously.
The supplementary vote system is used to elect Police and Crime Commissioners and directly elected mayors, including the Mayor of London, where there are more than two candidates. When there are only two candidates first past the post is used.
STV operates in multi-member constituencies. Voters rank candidates in order of preference by marking 1, 2, 3 etc against the candidates’ names on the ballot paper.
Voters can rank candidates within parties or across different parties. Candidates must obtain a certain quota of votes in order to be elected.
STV is used for local government elections in Northern Ireland and Scotland, European Parliament elections in Northern Ireland, and for Northern Ireland Assembly elections.
Under additional member systems, voters cast two votes. The first vote is cast for a constituency member using the system. The second vote, on a separate ballot paper, is for a party.
The percentage of votes obtained by each party determines their overall number of representatives. After taking into account the results of the constituency elections, additional seats are allocated to parties to the required degree of proportionality.
The additional member system is used for elections to the Scottish Parliament, the National Assembly for Wales and the London Assembly.
The Closed Party List system has been used for European Parliament elections in Great Britain since 1999. In Northern Ireland STV is used.
England is divided into nine regions, each of which is allocated a number of seats in relation to their electorate. Scotland and Wales each comprise a single region.
Voters mark a cross on the ballot paper next to the party they wish to vote for. Seats are then allocated according to the d’Hondt formula so that each party receives the number of seats proportionate to the votes it receives in the region.
The table in the PDF shows how five seats would be allocated between three parties receiving 700 (Party A), 400 (Party B) and 300 (Party C) votes respectively.
All three major political parties had included sections on the electoral system in their manifestos for the 2010 general election. The Conservative manifesto stated that the party supported the first past the post system; the Liberal Democrat manifesto supported STV; and the Labour manifesto included a commitment to hold a referendum on moving to AV.
The Parliamentary Voting System and Constituencies Act 2011 made provision for the next general election to be fought under the AV system, provided that the change was endorsed in a referendum.
A referendum was held on 5 May 2011 on whether the electoral system used for UK general elections should be changed from the first past the post system to the AV system. The referendum rejected the adoption of the AV.
The following are explained in more detail in the associated PDF:
The PDF includes information on a number of international comparisons and provides brief information on the voting systems used in the USA, Canada, India, Germany, New Zealand, France, Australia, Austria, Greece and Ireland which includes the following:
Commons Briefing papers SN04458
Author: Neil Johnston