Marginal Seat

If hypothetically you were to represent a type of parliamentary seat, then being a safe seat may sound like a good gig. You are reliable, usually loyal and predictable, which makes you easy to count on. These sound like great qualities, but ultimately, you are boring.  Being a marginal seat is where all the fun is at; you get all the press coverage, all the resources thrown at you and all the attention. You are an unpredictable wildcard, and you have the power to swing an election to a particular side, which makes you that bit much more important. Let's look at what exactly marginal seats are in this article.  

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Table of contents

    Meaning of marginal seat

    A marginal seat is a seat in parliament won only by a very small margin of votes, usually 10% or under. Marginal seats are critical to outcomes of general elections in the UK as they are incredibly unpredictable; it can even be the case that incumbent parties that lose their marginal seats lose their position as the leadership party, whereas the parties that gain marginal seats are better placed to form a government. Therefore, marginal seats are viewed as the 'battleground' of elections.

    A marginal seat is a constituency seat which is/was won by only a small margin. This means that only a small swing of votes can result in the seat being lost to an opposing side.

    Marginal seats in the UK

    In the UK, there are 650 constituencies, and therefore there are 650 seats in Parliament. Across the 650 constituencies, candidates put themselves up for election to gain a seat in parliament for either a political party or as an independent candidate.

    In order to form a government, a party needs 326 seats in parliament. Many of the seats in parliament are considered to be safe seats. There is not a consistent number of marginal seats in parliament, as the number of marginal seats differs depending on the outcomes of elections. Marginal seats are also hard to quantify precisely, as there is no clear-cut rule as to what margin percentage makes a seat marginal.

    This being said, seats won by a 10% or below margin are usually considered marginal seats and are of vital importance. This is because these seats only require a shift of around 5% of voters in the next election for the seat to fall into the hand of the opposition. In the last general election, there were 67 extremely marginal seats; these refer to seats that were won with a margin of less than 5%.1

    Marginal Seat Composition of the House of Common after the 2019 general election StudySmarterComposition of the House of Common after the 2019 general election, SeaghánÓ, CC0-1.0, Wikimedia Commons

    Safe seats are seats that are likely to be held by the incumbent party and have usually been won by a significant majority in the previous elections.

    As marginal seats are not easily predictable compared to safe seats, there is a larger focus on the voting outcomes of constituencies with marginal seats. These outcomes are viewed as where election results are made or break for the political parties. Therefore, even though only a minority of parliament seats are marginal, they hold great importance.

    Reasons for marginal seats

    The electoral system is why marginal seats exist and are so important in the UK. In the UK, the First-Past-the-Post (FPTP) system is used in general elections. This is a plurality system, meaning individual seats are awarded to candidates who receive the most votes but not necessarily the majority.

    The use of First Past the Post (FPTP) in the UK electoral system and questions about whether the UK electoral system requires reform is a topic you will have to be familiar with for your exams. FPTP is often criticised for this simple plurality system as it does not provide representation for those who did not vote for the winning candidate, nor do those elected require a majority. FPTP makes it possible for an individual to be elected as MP and gain a seat in parliament, despite the fact there may be more people who did not vote for them than those who did.

    The name First-Past-the-Post hints at how you can win using this electoral system- the party to win the most votes (that is, the first party past the post) wins. For more detail on this system, see our article First-Past-the-Post Voting.

    As a majority is not required for a Member of Parliament to be elected, FPTP allows for marginal seats, as the winner needs only to receive a few more votes than the other candidates, and therefore incredibly small marginal wins may be produced that could quickly shift in subsequent elections.

    If candidates A, B, and C were all running to win the constituency seat of Pickleberry East, Candidate A could receive 301 votes, Candidate B could receive 300 votes, and Candidate C could receive 67 votes. Even though more people collectively voted for B and C than A, Candidate A would win the seat (by only one vote), making that seat extremely marginal.

    In the 2015 general election, the winning party, The Conservatives, received only 37% of overall votes cast in the election, yet it ended up with 331 seats in parliament (over half). This is referred to as the winner's bonus and is viewed as a pitfall of FPTP. The winner's bonus refers to scenarios where the winning party gains several seats disproportionate to the share of votes they received nationally. This can occur when a large proportion of the seats won by the party are marginal seats where the winner received a smaller winning margin of votes.

    Examples of Marginal Seats

    As previously mentioned in the last general election (2019), of the 650 parliamentary seats, 67 seats were extremely marginal (a margin of under 5%).2

    The number of extremely marginal seats in the 2019 election had, however, reduced from the 2017 election, where 97 of the 650 parliamentary seats were extremely marginal. Let's look at some examples of marginal seats from general elections.

    In the 2017 general election, the Labour Party gained a marginal seat in the constituency of Kensington in London. At the time, Kensington was the third most marginal seat in the general election. The Labour Party gained the seat through a margin of just 20 votes. However, as is the very nature of marginal seats, there is always the possibility that such tight wins can easily be lost in the next general election. In the 2019 general election, the Conservative Party gained Kensington from the Labour Party by a margin of 150 votes. This means going forward, both the Conservative Party and the Labour Party will be maximising their efforts to either keep or gain Kensington in the next general election.

    In 2019, the constituency of North East Fife in Scotland was the most marginal seat of the entire general election. The Scottish National Party held on to this seat as a result of a mere two votes. That means if just one person forgot it was election day today, another decided to go to dinner after work instead of the polling station, and one person made a last-minute decision in the booth to vote for the Sottish Liberal Democrats instead of the SNP, the results would have been entirely different. This is how fragile the outcome of many of the most marginal seats are in the UK.

    Strategies For Securing Marginal Seats

    As mentioned, marginal seats can be the deciding factor when it comes to outcomes of general elections, and therefore they are given a lot of attention when campaigning. There are several strategies adopted by candidates and political parties to secure marginal seats.

    Talk to as many people as possible - To win over constituents' hearts and minds, candidates for constituencies and their teams often try to speak face to face with as many constituents as possible. This can take the form of knocking on doors, setting up local meetings and attending local events. Speaking to constituents face to face establishes a sense of familiarity between constituents and their MP, meaning that they are more likely to vote for them as there seems to be a more personable relationship between them. Political Parties usually prioritise these marginal seats on their political tours of the nation prior to the general election.

    Marginal Seat Former Labour Party Leader on his campaign tour of marginal constituencies StudySmarterJeremy Corbyn's campaign tour of marginal constituencies, Sophie Brown, CC-BY-SA.4.0, Wikimedia Commons

    Identify the most pressing concerns of the constituents - After talking to the constituents, MP's often identify the most pressing concerns raised by the constituents in marginal seats and present what solutions to these problems could emerge if they were to be elected. This makes many constituents more likely to vote for the MP as they believe not only were their concerns heard, but if elected, they will be solved.

    Perfect your campaign message - When campaigning, potential MP's must ensure that the messages they are sending to constituents within marginal seats are messages that will resonate with them. If there's a marginal seat in a region that once was a prestigious former coal mining town with a strong history of trade unions and a generally leftist atmosphere if you are an MP, it probably won’t go down well if your message is all about continued privatisation or how you want to replicate policies from former leaders such as Margaret Thatcher.

    Constituents within safe seats may often feel slighted or ignored, as they are often overlooked during general elections to focus on marginal seats. Constituents may feel they are being punished despite their loyalty, as many MPs do not make significant campaigning attempts in safe seats, as there's the assumption that the seat is all but guaranteed.

    This can often continue into terms as well; if a party realises that they hold a marginal seat and need to keep that seat in the next election, they might put more resources towards identifying and addressing the most pressing concerns for that constituency than they do for other constituencies where they hold a safe seat.

    Marginal Seat - Key takeaways

    • A marginal seat is a constituency seat which is won by only a margin.
    • There is a larger focus on the voting outcomes of constituencies with marginal seats than safe seats.
    • The use of First-Past-the-Post allows for marginal seats
    • Marginal seats with a margin of under 5% are considered extremely marginal.
    • T secure marginal seats, candidates will often increase their visibility in the constituency and speak to as many constituents as possible.
    • As marginal seats receive a lot of attention from political campaigners, those in safe seats can often feel ignored or like their votes are not valued.


    1. UK Parliament, General Election 2019: Marginality, 2020, Accessed August 2022
    2. UK Parliament, General Election 2019: Marginality, 2020, Accessed August 2022
    Frequently Asked Questions about Marginal Seat

    What is an example of a marginal seat?

    Kensington in London is an example of a marginal seat and has consistently changed hands over the last few general elections.

    How many marginal seats are there?

    It is hard to quantify how many marginal seats there are, but in the last general election there were 67 marginal seats that were won by a <5% margin.

    What is a marginal seat?

    A marginal seat is a constituency seat which was won by a small voting margin. This means that only a small swing of votes can result in the seat being lost to an opposing side.

    What is the importance of marginal seats?

    Marginal seats are important as they can be teh deciding factor in which political party is able to form a government. 

    Test your knowledge with multiple choice flashcards

    Which general election had the highest amount of extremely marginal seats?

    How many seats are required in order for a political party to form a government after a general election?

    What will most  political parties likely do in the run-up to general elections?


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