This note lists UK Parliamentary seats by marginality using the results from the 2017 General Election. All data is taken from the briefing paper General Election 2017: results and analysis.

Majorities are measured as the difference between the number of votes for the first and second placed candidates. Percentage majorities are those figures as a proportion of the total votes cast for all candidates. Percentage majorities are a better guide to relative marginality of different seats.

The top ten most marginal seats in GE 2017

North East Fife is the most marginal seat in the UK (in absolute and percentage terms) where the SNP beat the Liberal Democrats by just two votes.

Four of then most marginal seats are in Scotland. The most marginal seat in England – Kensington, in London – was the last result to be declared on the day after the election. It was won by Labour by a margin of 20 votes (0.1%).

The top ten least marginal seats in GE 2017

Liverpool Walton remains the safest seat in the UK. It was also the safest seat in the 2010 and 2015 General Elections. The second safest seat is Knowsley – a rank it also held in 2010 and 2015.

All of the ten least marginal seats are in England, with six being in the North West.

The number of marginal seats

In 2017 97 seats were won by a margin of 5% or less of votes cast – an increase on the 56 won by this narrow margin in the 2015 Election, and slightly more than the 91 in this category in the 2010 Election.

The number of very safe seats also increased in this election. Seats won by a margin of over 50% increased from 21 in 2015 to 35 in 2017, while the number of seats won by a margin of between 45% and 50% increased from 18 to 29.

This paper contains three sets of tables:

  1. Parties by majority: this is a list of seats won by each party along with their majority, the rank of their majority (smaller numbers indicate more marginal seats), and the second placed candidate;
  2. All seats by majority: this list is similar to the first, although it shows all constituencies in alphabetical order. This can be used to determine how marginal a seat is compared to all others;
  3. Three-way marginal seats: this is a list of the constituencies where the third placed candidate in 2017 is within 20 percentage points of the winner;
  4. Target seats: this is a list that shows potential future target seats for selected parties. This has been calculated as the difference between the winning party’s vote total and the selected party.

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