Different Voting Systems used in the UK

Comparison of first-past-the-post (FPTP) to a different electoral system in a devolved parliament/assembly

Voting systems with music.mp3

In this podcast from the Politics Shed, I give an overview of all the current voting systems used in the UK as well as some that have been used or might have been used. I describe the strengths and weaknesses of each.

First Past the Post FPTP

Used: House of Commons and in England and Wales for local government.


It is a constituency system. Currently, there are 650 parliamentary constituencies in the UK.

• Voters select a single candidate, and do so by marking his or her name with an ‘X’ on the ballot paper. This reflects the principle of ‘one person, one vote’.

Constituencies are of roughly equal size, which is ensured by reviews by the Electoral Commission and the Boundary Commissions for Scotland and Northern Ireland.

• Each constituency returns a single candidate. This is often seen as the ‘winner-takes-all’ effect. (However, there are still a small number of multimember constituencies in local government.)

• The winning candidate needs only to achieve a plurality of votes. This is the ‘first-past-the-post’ rule.

For example, if votes were cast as follows:

Candidate A = 30,000 votes

Candidate B = 22,000 votes Candidate

C = 26,000 votes

Candidate A would win, despite polling only 38 per cent of the vote.

Follow link for strengths and weaknesses -First Past the Post -

Additional Member System AMS

Scottish Parliament, Welsh Assembly, Greater London Assembly.


It is a ‘mixed’ system, made up of constituency and party-list elements.

• A proportion of seats are filled by ‘first past the post’, using single-member constituencies. In Scotland and London, 56 per cent of representatives are elected in this way. In Wales, this figure is 66 per cent.

• The remaining seats are filled using a ‘closed’ party-list system.

• Electors cast two votes: one for a candidate in a constituency election and the other for a party in a list election.

• The party-list element in AMS is used to ‘top up’ the constituency results. This is done ‘correctively’, using the D’Hondt method (devised by the Belgian mathematician Victor D’Hondt), to achieve the most proportional overall outcome.


The mixed character of this system balances the need for constituency representation against the need for electoral fairness.

• Although the system is broadly proportional in terms of its outcomes, it keeps alive the possibility of single-party government.

• It allows voters to make wider and more considered choices. For example, they can vote for different parties in the constituency and list elections.


The retention of single-member constituencies reduces the likelihood of high levels of proportionality.

• The system creates confusion by having two classes of representative.

• Constituency representation will be less effective than it is in FPTP, because of the larger size of constituencies and because a proportion of representatives have no constituency duties.

Additional Member System

Single Transferable Vote STV

Used: Northern Ireland Assembly, in Northern Ireland and Scotland for local government, and in Northern Ireland only for European Parliament.


There are multimember constituencies. The Northern Ireland Assembly has 18 constituencies, each returning 6 members. In local elections in Northern Ireland there is a mixture of 5–6-and 7-member constituencies.

• Political parties are able to put up as many candidates as there are seats to fill in each constituency.

• Electors vote preferentially.

• Candidates are elected if they achieve a quota of votes. This quota is calculated on the basis of the Droop formula

• If this process still leaves some seats unfilled, the candidate with the fewest votes drops out and his or her votes are redistributed according to second or subsequent preferences.


The system is capable of achieving highly proportional outcomes.

• Competition amongst candidates from the same party means that they can be judged on their individual records and personal strengths.

• The availability of several members means that constituents can choose who to take their grievances to.

• Votes are counted, first, according to first preferences. If any candidate achieves the quota, additional votes for him or her are counted according to second or subsequent preferences.


The degree of proportionality achieved in this system can vary, largely on the basis of the party system.

• Strong and stable single-party government is unlikely under STV.

• Multimember constituencies may be divisive because they encourage competition amongst members of the same party.

Single Transferable Vote

Regional Party List


European Parliament (except Northern Ireland where STV was used).


There are a number of large multimember constituencies. When the UL was in the EU and voted in elections, the UK was divided into 12 regions, each returning 3–10 members (72 in total).

• Political parties compile lists of candidates to place before the electorate, in descending order of preference.

• Electors vote for parties not for candidates. The UK uses ‘closed’ list elections.

• Parties are allocated seats in direct proportion to the votes they gain in each regional constituency. They fill these seats from their party list.


It is the only potentially ‘pure’ system of proportional representation, and is therefore fair to all parties.

• The system tends to promote unity by encouraging electors to identify with a region rather than with a constituency.

• The system makes it easier for women and minority candidates to be elected, provided they feature on the party list.


The existence of many small parties can lead to weak and unstable government.

• The link between representatives and constituencies is significantly weakened and may be broken altogether.

• Parties become more powerful, as they decide where candidates are placed on the party list.

Regional List

Supplementary Vote SV


London mayoral elections. Features:

• Single-member constituencies. • Electors have two votes: a first preference vote and a second, or ‘supplementary’, vote.

• Winning candidates in the election must gain a minimum of 50 per cent of all votes cast.

• Votes are counted according to first preference. If no candidate reaches 50 per cent, the top two candidates remain in the election and all other candidates drop out, their vote being redistributed on the basis of their supplementary vote.


SV is ‘simpler’ than AV, and so would be easier for voters to understand and use.

• The focus on gaining second-preference or supplementary votes, encourages conciliatory campaigning and a tendency towards consensus.


Although fewer votes are ‘wasted’ in SV compared with FPTP, unlike AV, SV does not ensure that the winning candidate has the support of at least 50 per cent of voters (because a proportion of supplementary votes will be for candidates who have dropped out).

• The emphasis on making supplementary votes count may encourage voters to support only candidates from the main parties, perhaps discouraging them from supporting their preferred second-preference candidate.

Supplementary Vote

Alternative Vote AV


Scottish local by-elections, Labour and Liberal leadership elections, and by-elections for hereditary peers.


There are single-member constituencies.

• Electors vote preferrentially by ranking candidates in order (1, 2, 3 and so on).

• Winning candidates in the election must gain a minimum of 50 per cent of all votes cast.

• Votes are counted according to first preference. If no candidate reaches 50 per cent, the bottom candidate drops out and his/her votes are redistributed according to second or subsequent preferences, and so on, until one candidate gains 50 per cent.


AV ensures that fewer votes are ‘wasted’ than in FPTP.

• As winning candidates must secure at least 50 per cent support, a broader range of views and opinions influence the outcome of the election, with parties thus being drawn towards the centre ground.

Disadvantages: • The outcome of the election may be determined by the preferences of those who support small, possibly extremist, parties.

• Winning candidates may enjoy little first-preference support and only succeed with the help of redistributed supplementary votes, making them only the least unpopular candidate.