The 4 July general election was a massive success for Labour, returning 411 seats for the party and an 86-seat majority. However, while Labour now holds 63.2% of the seats in the House of Commons, it only received 33.5% of the national-level vote. In contrast, Reform UK took 14.3% of votes but only 0.8% of seats (5 in total).
The discrepancy between votes and seats have led some to argue for reforms to the UK’s electoral system to ensure a more proportional result. The table below shows how many seats each party would have won under the most permissive electoral system – proportional representation (PR), with the entire country as a single constituency and no statutory minimum percent of votes to gain a seat.
| Party | %Vote | FPTP Seats | %FPTP Seats | PR Seats | %PR Seats | Seats Lost/Gained Under PR |
| Labour | 33.7 | 411 | 63.2 | 230 | 35.4 | -181 |
| Conservative | 18.6 | 121 | 18.6 | 161 | 24.8 | +40 |
| Liberal Democrat | 12.2 | 72 | 11.1 | 83 | 12.8 | +11 |
| SNP | 2.5 | 9 | 12.2 | 17 | 2.6 | +8 |
| Sinn Féin | 0.7 | 7 | 1.1 | 4 | 0.5 | -3 |
| Reform UK | 14.3 | 5 | 0.8 | 97 | 14.9 | +92 |
| DUP | 0.6 | 5 | 0.8 | 4 | 0.6 | -1 |
| Green | 6.4 | 4 | 0.6 | 43 | 6.6 | +39 |
| Plaid Cymru | 0.7 | 4 | 0.6 | 4 | 0.6 | 0 |
| SDLP | 0.3 | 1 | 0.3 | 2 | 0.3 | + |
| Alliance | 0.3 | 1 | 0.2 | 2 | 0.3 | +1 |
| UUP | 0.2 | 1 | 0.2 | 2 | +1 | |
| TUV | 0.2 | 1 | 0.2 | 1 | 0.2 | 0 |
While the fairness of the first past the post (FPTP) system is a topic worthy of debate, there are significant problems with extrapolating what seats a party would win under PR based on the FPTP votes they receive. As this blog will explore, electoral rules shape both voter and party behavior. In turn, these behavioral changes can create party systems that introduce their own set of practical and ethical challenges.
(Dis)proportionality of electoral systems
The proportionality of an electoral system refers to the similarity between a party’s vote share in the election and their seat share in the legislature. In a highly proportional system, vote and seat shares are closely aligned, meaning a party that wins 10% of the vote would hold 10% of seats in parliament. The main constraint on the proportionality of an electoral system comes from how many seats are elected in each district, known as the district magnitude (DM). Because parties cannot earn a fraction of a seat, higher district magnitudes allow for greater proportionality because there are more granular ways to assign seats. For example, consider a party that wins 12% of the vote in a constituency where DM=10: 12% of 10 seats is 1.2 and there is no way to give a party .2 of a seat. Instead, the party would only get 1 seat, leading to a disparity between vote and seat share. In contrast, a constituency with DM = 100 can give 12 seats, leading to a perfectly proportional result.
Electoral systems with a DM=1, such as FPTP, are inherently disproportional because there is no way to divide up 1 seat between parties. Thus, a party can win either 100% of the seats in the district (1 seat), or 0%. For example, a constituency where one party gets 51% of the vote and the other has 49% means that the party with 51% would get the seat, while the one in second would get nothing, leading to a nearly 50% disparity between vote and seat shares. This issue is compounded when more than two parties gain votes in a constituency because it is possible to gain a seat with even less than 50% of the vote. Indeed, the median vote share of England’s winning candidates in 2024 was 41.2%, meaning that in most constituencies, the majority of voters did not cast their ballots for the candidate who won.
Electoral systems and behavior, implications for the UK
The disproportionality of results under a FPTP system significantly influences how both parties and voters behave, because votes do not contribute equally to how many seats a party can win. In a highly proportional system, more votes inherently translate to more seats. However, the same does not hold for FPTP elections. As long as a candidate under FPTP wins more votes than anyone else, additional votes are worth nothing – winning by a 1% margin produces the exact same result as winning by 30%.
Changes in voter behaviour
Under FPTP and other disproportionate systems, voters can have incentives to choose a candidate that is not their most preferred and instead vote against the candidate they dislike the most. Rather than “wasting” their vote for a candidate that has little to no chance of winning, voters may instead choose to support the candidate that is most likely to defeat their least preferred candidate. In this election, voters may have chosen to support Labour even if they preferred the Liberal Democrat platform to prevent a Conservative victory. Similarly, some Conservative voters may have preferred Reform’s policies, but felt that the Reform candidate had no chance of winning in their constituency.
Changes in party behaviour and party systems
Electoral systems have a significant impact party behavior, platforms, and even what parties exist within a country. FPTP encourages a strategic deployment of campaign resources based on how likely a candidate is to win or lose in a given constituency — there is little value from time and money spent in areas where a party’s candidate is virtually guaranteed to win nor those where they will certainly lose.
Instead, parties focus on constituencies with more uncertain outcomes, where persuading a relatively small number of voters to either change (in the case of non-incumbents) or not change (in the case of incumbents) their vote can significantly alter the chances of victory. This year, the Liberal Democrats were remarkably successful with their deployment of resources, gaining 64 additional seats with only 0.6% more votes. In contrast, under PR, parties focus more on total votes, rather than high value votes in specific constituencies.
Electoral systems also have a significant impact on what parties even exist within a country. While FPTP encourages larger parties representing a broader coalition of interests, PR allows for a party system with smaller and more numerous parties. Groups with relatively similar interests have an incentive to stick together under FPTP while they would be able to split into separate parties. While it is true that multiple parties typically win seats in the House of Commons, the UK is generally considered to be a two-party system (at least at the national level) because for over 100 years, either the Conservatives or Labour almost always win a majority of seats and are able to govern alone. PR systems, particularly those with large district magnitudes, are less likely to produce parties that regularly gain a majority of seats.
The drawbacks of highly proportional systems
On its face, a system that reduces “wasted” vote and ensures a close connection between voter preferences and parliamentary representation, such as PR, seems highly desirable. However, the institutional incentives that allow for multiple parties to gain significant representation can create fractured party systems that lead to practical and ethical concerns. These issues are particularly prevalent in PR systems with high district magnitudes.
The main practical consideration is that of government formation. When a party earns more than 50% of seats, government formation is generally simple – the majority party becomes the government. Single-party majority governments also tend to be quite stable, because there are no concerns about a party leaving the government and causing it to lose majority support. In contrast, government formation can become extremely difficult, if not impossible, when it requires agreement between multiple parties. For example, the most recent election in the Netherlands took place on 22 November, 2023 with 15 parties gained seats and the largest, the PVV, holding only 37 (24.6%). It was not until 2 July 2024 that a new government was sworn in, containing four parties, any of which could cause the government to fail if it leaves.
The process of government formation under a fractured party system can create ethical concerns because there is less connection and more uncertainty between how many seats a party gets and the government that forms after the election. When the Conservatives and Liberal Democrats formed their coalition in 2010, a common refrain from critics was that “nobody voted for this government”. If they UK were to switch from FPTP to high-DM PR, this situation would become the norm, rather than the exception.
In general, the party that wins the most seats has a better (though not guaranteed) chance of being part of the government. However, for smaller parties, gaining more seats does not necessarily increase their chances of entering government. In fact, it may actually decrease their suitability as a coalition partner because there is a strong correlation between the proportion of seats a party holds in the cabinet and how many portfolios they are allocated. Therefore, a party may become a less attractive coalition partner if they gain more seats. At the same time, smaller parties may be able to extract significant policy concessions by putting themselves in the “kingmaker” position if they would be willing to cooperate with different sets of parties. In Germany, the FDP has been able to have a historically strong influence on German economic and fiscal policy because they are willing to cooperate with both the center-right CDU/CSU and center-left SPD. The disconnect between party size and their coalition potential can also make it harder for voters to punish parties they disagree with. For example, the ÖVP in Austria has been part of every government since 1999, despite placing anywhere from first to third and vote shares ranging between 26 and 42%.
Conclusion
Without a legislature comprised of every voter in a country, there is no way to fully represent the range of all voter’s preferences. While high-DM PR generally allows for the representation of a wider range of views, such representation may make governing difficult or even impossible. Voters will also frequently have less say on which parties enter or leave government. FPTP significantly minimizes these issues, but gives up the advantage of proportionality. While Labour was the biggest beneficiary from FPTP’s disproportionality earlier this month, both Labour and the Conservatives have consistently benefited from FPTP’s disproportionality. As such, both parties have limited incentive to change it of their own accord. Indeed, the AV referendum in 2011 only occurred when the Liberal Democrats were able to introduce it as a condition of the coalition agreement. Electoral system reform, particularly to the extent of high-DM PR is unlikely to occur without a similar situation that gives more power to smaller parties who would benefit from such a change.
Kathryn Wainfan.
Kathryn Wainfan holds a PhD in Political Science from the University of California, Los Angeles. She has been a lecturer in Political Science at the University of California, Los Angeles, University of California, Merced, and Loyola Marymount University.
The Constitution Society is committed to the promotion of informed debate and is politically impartial. Any views expressed in this article are the personal views of the author and not those of The Constitution Society.