The UK does not have one electoral system - it has several running at once. First past the post elects the House of Commons; AMS elects the Scottish Parliament and (until 2026) the Welsh Senedd; STV elects the Northern Ireland Assembly; SV elected the Mayor of London until 2022. This walk-through covers how each system works, what each one produces, and the live debate: after 2024, should FPTP be replaced? It finishes with a worked 30-mark essay. Three short quizzes break the tour up.
Every electoral system answers the same question - how do votes become seats? - and every answer involves a trade-off. First past the post (FPTP) trades proportionality for strong single-party government and a clear local MP. Proportional systems trade clear winners for fairness between parties. The 2024 general election put the trade-off on the front page: Reform UK won 14.3% of the vote and 5 seats, while Labour won 411 seats - a 174-seat majority - on 33.7%. The spec asks you to know four systems (FPTP, AMS, STV, SV), to weigh their advantages and disadvantages, and to compare FPTP with a system used in a devolved parliament or assembly. The exam asks the question underneath all of that: which trade-off should the UK make?
The mechanics first, because every strength and weakness follows from them.
FPTP is a plurality system: the UK is divided into 650 single-member constituencies, each voter puts one cross next to one candidate, and the candidate with the most votes wins the seat. Not a majority of votes - just more than anyone else. A government is then formed by whichever party can command the confidence of the Commons, which usually means the party with the most seats.
Two consequences flow straight from the mechanics. First, wasted votes: every vote for a losing candidate, and every vote for a winning candidate beyond what was needed to win, has no effect on the result. The 2019 Pearson mark scheme makes the point directly: governments and MPs gain election with less than 50% of the vote and then exercise majority power on a minority vote. Second, geography decides everything: a party whose support is spread thinly across the country can pile up millions of votes and win almost nothing, while a party whose support is concentrated converts a small national share into many seats. In 2024, Reform UK's 14.3% produced 5 seats while the SNP's 2.5% produced 9 - concentration beat size.
FPTP's defenders make a trade-off argument, not a fairness one. The 2019 mark scheme carries their case: FPTP delivers strong and stable government able to carry out its manifesto and be held accountable at the next general election; it provides a good MP-constituency link because constituencies are relatively small and every voter has one clear representative; it is clear and easy to understand, with few spoiled ballots; and it has an impressive record of keeping out extremist parties, whose support is rarely concentrated enough to win seats.
The critics answer with the same mark scheme's other column: FPTP damages legitimacy and discourages turnout because of the wasted vote; it breeds adversarial politics and negates the need for compromise; and its winner-takes-all approach delivers extremes of policy change, with incoming governments driven to undo their predecessors' work. Both columns are board-approved arguments - the essay skill is weighing them, not listing them.
Scroll - each system lights with where it is used and how it works.
The spec names four systems: FPTP, the Additional Member System (AMS), the Single Transferable Vote (STV) and the Supplementary Vote (SV). The point of learning all four is comparison - spec point P1.3.1.c requires you to compare FPTP with a different system used in a devolved parliament or assembly, which in practice means AMS (Scotland and Wales) or STV (Northern Ireland). Scroll through; the figure beside you holds the four system cards with the one you are reading lit.
The UK runs different systems for different bodies. Westminster keeps FPTP; the devolved bodies were given more proportional systems when they were set up in the late 1990s. That choice - and what it has produced - is spec point P1.3.3.a: the debate on why different systems are used in the UK.
650 single-member constituencies. One vote, one cross. The candidate with the most votes - a plurality, not a majority - wins. The party able to command the confidence of the Commons forms the government.
A hybrid. Each voter has two votes: one for a constituency member elected under FPTP, and one for a party on a regional list elected under closed-list proportional rules. The list seats are top-up seats: they are allocated to correct the disproportionality the FPTP half produces, so the overall chamber comes closer to the vote share.
Multi-member constituencies - several seats per area. Voters rank candidates 1, 2, 3 and so on, across and within parties. A candidate is elected on reaching the Droop quota; surplus votes from elected candidates and votes from eliminated candidates transfer to voters' next preferences until all seats are filled.
A majoritarian system for single-winner posts. The voter marks a first and a second choice. If no candidate wins a majority of first choices, all but the top two are eliminated and the second choices of eliminated candidates are added on. The winner therefore has a broader mandate than a plain plurality.
Wales is abandoning AMS. From 2026 the Senedd moves to a closed-list proportional system with a larger 96-seat chamber. Put alongside the Elections Act 2022 moving mayors the other way - from SV to FPTP - the UK is currently changing electoral systems in both directions at once. That is a ready-made evaluation point for any "different systems" question.
Scroll - each effect lights so you can compare the systems across, not one after another.
Spec points P1.3.3.b and P1.3.3.c ask for the impact of the systems on three things: the type of government appointed, party representation, and voter choice. These are the themes the 30-mark questions are built on - so learn the systems across each theme, not one system at a time.
Government type, party representation, voter choice. For each one, FPTP sits at one end and STV at the other, with AMS in between. That spread is what makes the comparison questions work.
But note the strain. The 2022 Pearson mocks mark scheme points out that out of the recent run of governments, two needed the support of other parties to be in office - the 2010-15 coalition and the 2017 confidence and supply agreement with the DUP. FPTP no longer guarantees the strong single-party government it promises.
The party-system point. The 2022 mocks mark scheme frames it as a debate: at Westminster the system works in the interests of two parties and produces vast numbers of safe seats - but in the devolved regions a multi-party system has operated for decades, and the mark scheme attributes that directly to the different voting systems. By vote share, 2024 was genuinely multi-party (six parties above 6%); by seats, FPTP still delivered a single-party landslide.
The counter. Choice has a cost: closed lists hand power over candidate order to party leaders (the 2019 mark scheme's "PR would hand excessive power to parties" point), and STV counts are complex. Simplicity is a form of voter power too.
Pick the theme the question is about - government, representation or choice - and run FPTP against a devolved comparator inside that theme. Pair every strength with its cost: strong government rests on manufactured majorities; proportional fairness rests on post-election deals voters never voted for. Then judge which cost is easier to live with.
Scroll - each argument lights with its strongest evidence and its counter.
This is the question the whole topic builds towards, and 2024 sharpened it. The two main parties' combined vote share fell to its lowest in modern history (around 57%), the Hansard Society's 2024 audit flagged the FPTP distortion as a concerning new high, and the Electoral Reform Society continues its long campaign for PR. Against that, the 2011 AV referendum result still stands as the public's last word, and FPTP's defenders argue the 2024 result proves the system still does its core job - it threw out a government decisively. Scroll through the four argument pairs.
Fair representation, government quality, the voter's experience, and stability versus extremism. Every Pearson mark scheme on this topic is built from these pairs - the skill is running both sides of each pair and judging, not listing one column.
The strongest essays do not split the difference. Decide which side carries more weight after 2024 and hold the line through every pair. The reform case has the momentum of the evidence; the keep case has the 2011 referendum and the accountability argument. Either line can reach the top band - fence-sitting cannot.
How the topic is tested, with approaches to the recurring questions.
Electoral systems appears in Paper 1 as a 30-mark question - either Q1, the source question, or Q2, the essay. Both split AO1/AO2/AO3 at 10/10/10. The rules are the same for both: two views, weighed in a balanced way, with a clear and sustained line of argument - a one-sided answer is capped at Level 2. On the source question, analysis and evaluation must work from the information in the source; outside evidence earns its place only when it develops a source point. Conclusions justify, they do not summarise.
Recurring 30-mark questions to practise.
Approach: Pair the source points. Para 1 - legitimacy: wasted votes and minority-vote majority power against accountability through single-party government held to its manifesto. Para 2 - the voter: unequal votes and deterred small-party supporters against the simple ballot, few spoiled papers and the MP-constituency link. Para 3 - power: a more reflective Parliament for a multi-party society against PR handing excessive power to parties through post-election deals and leader-controlled lists. Pick a side in the introduction and hold it through three interim judgements.
Approach: Theme by theme, not system by system. Para 1 - representation: the devolved chambers track vote share and run multi-party politics (2022 mocks MS attributes the devolved multi-party systems directly to the different voting systems), against the confusion of running several systems at once. Para 2 - government: power-sharing and coalition as a feature in Belfast and Edinburgh, against the loss of single-party decisiveness. Para 3 - the voter: more choice (two votes under AMS, full ranking under STV) against complexity - and note Wales is abandoning AMS for a closed-list system in 2026, so even the beneficiaries keep changing their minds.
Approach: The debate section above is the plan: fairness, government quality, the voter, stability. Whichever side you take, every paragraph must carry both views and end with an interim judgement on your side. The 2024 evidence (Reform 14.3% and 5 seats; Labour's 174-seat majority on 33.7%; the two main parties' combined share at a modern low) is the freshest material - and post-2024 material is what examiners expect for 2026.
Approach: The electoral-systems angle runs through this party question. Agreement - FPTP operates to the benefit of the two established parties, with vast numbers of safe seats, and PMs have come from only two parties since 1945. Disagreement - two of the recent governments needed other parties (the coalition, the DUP deal); the devolved regions run multi-party systems built on different voting rules; and smaller parties shape the big issues. Judgement: two-party in Commons seats, multi-party in votes and in the devolved bodies - say which measure matters more and why.
Judgement. FPTP should be replaced. Its defenders' best arguments - stability, accountability, the local MP - are either weakening in practice or preserved under AMS, while its central defect, the gap between votes and seats, grew to a modern extreme in 2024. The 2011 referendum rejected one alternative, AV, not the principle of reform; the question for Westminster is no longer whether the distortion exists, but how long a multi-party electorate will accept a two-party system built on it.
Plurality. More votes than any other candidate - not necessarily a majority. The FPTP winning condition.
Majoritarian system. A system designed to produce a clear winner rather than a proportional chamber. FPTP and SV are in this family.
Proportional representation (PR). Any system that aims to match a party's share of seats to its share of votes. STV is proportional; the list element of AMS is proportional.
First past the post (FPTP). 650 single-member constituencies; one cross; the plurality winner takes the seat. Elects the House of Commons.
Additional Member System (AMS). Hybrid: FPTP constituency members plus regional closed-list top-up seats that correct the disproportionality. Scottish Parliament since 1999; Welsh Senedd 1999-2026.
Single Transferable Vote (STV). Multi-member constituencies; voters rank candidates; election on reaching the Droop quota; surpluses and eliminated candidates' votes transfer. Northern Ireland Assembly and Scottish councils.
Supplementary Vote (SV). First and second choice for a single-winner post; top-two run-off if no majority. Used for the London Mayor until the Elections Act 2022 switched mayors and PCCs to FPTP.
Droop quota. The vote total a candidate must reach to be elected under STV.
Wasted vote. A vote that does not affect the result - cast for a loser, or surplus to a winner's needs. The core FPTP criticism.
Safe seat. A constituency one party is effectively certain to win. The 2022 mocks mark scheme cites the vast number of Labour and Conservative safe seats as evidence the system serves two parties.
Manufactured majority. A Commons majority won on a minority of the vote - 2019 (43.6% into a majority of 80) and 2024 (33.7% into a majority of 174).
Tactical voting. Voting for a less-preferred candidate with a better chance of beating the candidate you oppose - a rational response to FPTP.
Top-up seats. The list seats under AMS, allocated to bring the chamber closer to the vote share.
Closed list. A list system where the party fixes the order of its candidates - the basis of the mark scheme's point that PR can hand power to party leaders. The system the Senedd adopts from 2026, with a larger 96-seat chamber.
Elections Act 2022. The Act that moved mayoral and police and crime commissioner elections from SV to FPTP, first applying in 2024.
2011 AV referendum. The UK-wide vote that rejected replacing FPTP with the Alternative Vote - the keep side's standing answer to reform demands.
Electoral Reform Society. The long-running campaign organisation for proportional representation.
Hansard Society. The research body whose democracy audits track the system's health; its 2024 audit flagged the FPTP distortion as a concerning new high.