How do the UK's electoral systems work, and should Westminster keep first-past-the-post?
Component 3.1: the features, advantages and disadvantages of FPTP, AMS, STV and SV, and the comparison of first-past-the-post with a proportional system used in a devolved body.
An Edexcel A-Level Politics Component 1 answer on electoral systems, covering how first-past-the-post, the Additional Member System, the Single Transferable Vote and the Supplementary Vote work, their advantages and disadvantages, and a comparison of FPTP with the proportional systems used in the devolved bodies.
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What this dot point is asking
Edexcel wants you to explain how first-past-the-post (FPTP), the Additional Member System (AMS), the Single Transferable Vote (STV) and the Supplementary Vote (SV) work, their advantages and disadvantages, and to compare FPTP with a proportional system used in a devolved parliament or assembly. This is examined through the 30-mark source and essay questions.
First-past-the-post (FPTP)
Advantages. It is simple to use and understand; it usually produces a single-party government with a working majority, giving strong and accountable government; it maintains a clear constituency link between one MP and one area; and it tends to exclude extremist parties.
Disadvantages. It is highly disproportional: a party can win a Commons majority on well under half the vote, and small parties with dispersed support win few seats (in 2015 UKIP won around 12.6 per cent of the vote and one seat). It produces many wasted votes in safe seats, depresses turnout, and can give a winner's bonus that distorts the result. Marginal seats receive disproportionate campaign attention.
The Additional Member System (AMS)
AMS combines the constituency link of FPTP with much greater proportionality, but it creates two classes of representative (constituency and list members) and can give list parties a strong role.
The Single Transferable Vote (STV)
STV, used for the Northern Ireland Assembly and Scottish local elections, uses large multi-member constituencies. Voters rank candidates in order of preference; candidates reaching a quota are elected and their surplus votes are transferred. STV delivers high proportionality and wide voter choice (including between candidates of the same party), and in Northern Ireland it supports power-sharing. Its drawbacks are a weaker single-member link, a complex count, and a tendency toward coalition government.
The Supplementary Vote (SV)
SV was used to elect mayors (including the London Mayor until 2021, when it switched to FPTP) and police and crime commissioners. Voters mark a first and second preference; if no candidate wins a majority of first preferences, all but the top two are eliminated and second preferences are redistributed, so the winner has broad support. It is simple and ensures majority backing but can eliminate a candidate with wide second-preference appeal.
Examples in context
- 2015 general election (UKIP), around 12.6 per cent of the vote for one seat, the classic FPTP disproportionality example.
- The Scottish Parliament under AMS, producing SNP minority and coalition governments rather than single-party majorities.
- The Northern Ireland Assembly under STV, supporting proportional, power-sharing representation.
- The London Mayor, elected by SV until 2021 and by FPTP since, a useful illustration of how the system shapes the contest.
Try this
Q1. Explain and analyse three advantages of first-past-the-post. [9 marks]
- Cue. Strong single-party government, a clear constituency link, and simplicity, each developed with an example.
Q2. Evaluate the view that proportional representation should be used for all UK elections. [30 marks]
- What the marker wants. A two-sided AO1 to AO3 essay weighing proportionality and reduced wasted votes against strong government and the constituency link, reaching a justified judgement.
Exam-style practice questions
Practice questions written in the style of Pearson Edexcel exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Edexcel 201920 marksEvaluate the view that first-past-the-post should be replaced for elections to the House of Commons. Reworded from a 30-mark essay to fit the schema; argue both sides and reach a judgement.Show worked answer →
A Section A 30-mark essay (shown as 20) on AO1, AO2 and AO3. Build two-sided arguments comparing FPTP with a proportional alternative.
For replacement: FPTP is highly disproportional (in 2015 UKIP won around 12.6 per cent of the vote but one seat; in 2024 Reform UK won around 14 per cent and five seats), wastes votes in safe seats, and excludes smaller parties, producing a democratic deficit.
Against replacement: FPTP is simple, produces a clear single-party government and a strong constituency link, usually delivers decisive outcomes, and avoids the coalition bargaining and extremist representation that PR can bring.
A Level 5 answer judges, for example, that FPTP's disproportionality is a real flaw but its strong government and constituency link explain why it survives, then sustains that line.
Edexcel 202120 marksExplain and analyse three differences between first-past-the-post and the Single Transferable Vote. Edexcel 9-mark 'explain and analyse' style; develop each point.Show worked answer →
An "explain and analyse three" question is AO1 and AO2 only. Choose three clear differences and develop each.
One: proportionality, where STV produces results closely matching vote share in multi-member constituencies while FPTP can give a party a majority of seats on a minority of votes. Two: constituency type, where STV uses large multi-member constituencies and FPTP uses single-member constituencies, affecting the MP to voter link. Three: voter choice, where STV lets voters rank candidates (including within a party) while FPTP allows only a single X.
Markers reward three accurate, distinct differences, each developed with an example such as the Northern Ireland Assembly (STV) versus Westminster (FPTP).
Related dot points
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- Component 1.1 to 1.2: representative and direct democracy, the widening of the franchise and debates over suffrage, the participation crisis and the case for reform.
An Edexcel A-Level Politics Component 1 answer on democracy and participation, covering the features of representative and direct democracy, the widening of the franchise from the 1832 Great Reform Act to the 1969 Representation of the People Act, the participation crisis and democratic deficit, and the case for reform.
- Component 3A.6.9 to 6.10: comparing and debating UK and US democracy and participation (party systems, internal party unity, party policy profiles, campaign finance and pressure groups), and how rational, cultural and structural approaches account for the differences.
An Edexcel A-Level Politics Component 3 answer comparing UK and US democracy and participation, covering the two-party and multi-party systems, internal party unity, the policy profiles of the main parties, campaign finance and party funding, and the power and methods of pressure groups, explained through rational, cultural and structural approaches.
Sources & how we know this
- Pearson Edexcel A-Level Politics (9PL0) specification — Pearson Edexcel (2017)