The 2017 General Election had the highest turnout since 1997, and some very marginal wins made headlines. In this post, we look at the figures on marginality and turnout.

The number of very safe and very marginal seats has increased…

Of the 650 Parliamentary constituencies, 97 were won by a margin of 5% or less of votes cast – a sharp 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 markedly 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.

Which were the safest seats?

Liverpool Walton remains the safest seat in the UK (ranked in terms of the victor’s winning margin of votes over the second placed candidate as a % of all valid votes cast). 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.

The table below shows the 30 safest seats in the UK. Of these, 13 seats are in London and 11 seats are in the North West of England (including the top five, all in Merseyside).

The 28 safest seats are all Labour holds and the top 21 were won with majorities of over 60%.

The safest Conservative seat is Christchurch, the 37th safest seat in the UK.

Which were the most marginal seats?

In the 2017 General Election 31 seats (listed in the table below) were won with majorities of less than 1% of valid votes cast (compared with 13 in 2015 and 23 in 2010).

Within the list of 31 most marginal seats in 2017, a remarkably high proportion (12 seats) are in Scotland, comprising eight SNP holds, three Labour gains from the SNP and one Conservative gain from the SNP. The most marginal seat in the UK is North East Fife, where the SNP beat the Liberal Democrats by just 2 votes.

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 (0.05%).

11 seats were won by fewer than 100 votes in this election, compared with three in 2015 and six in 2010.

An increase in turnout

Turnout was 68.8% across the UK, a slight increase compared with 65.1% in 2010 and the highest general election turnout since 1997.

Among the countries and regions of the UK:

 – Turnout in England was the highest of any UK country (69.1%)

 – Turnout was highest in the three southernmost English regions: the South West (71.8%), the South East (71.2%) and London (70.1%) had turnout of over 70%

 – Turnout in Scotland was 66.4%, down from 71.0% in 2015

 – Northern Ireland again had the lowest turnout (65.4%) but it saw the highest increase in turnout compared with the previous General Election (up by 7.3 percentage points).

Where was turnout highest and lowest?

The constituency with the highest turnout was Twickenham (79.5%), which the Liberal Democrats won back from the Conservatives. Twickenham had the 4th highest turnout in the UK in 2015 (77.4%) and the highest in England (the top three spots were taken by Scottish constituencies in 2015).

Of the 30 highest constituency turnouts, eight were in the South East region. 16 of the top 30 were won by the Conservatives.

Of the 30 constituencies with the lowest turnout, 24 were won by Labour and 9 were in the Yorkshire and the Humber region. Glasgow constituencies accounted for 4 of the 10 lowest constituency turnouts in the UK.

Average turnout in the 12 seats won by the Liberal Democrats was 75.0%. Turnout in seats won by the Conservatives (70.8%) was 4.2 percentage points higher than in seats won by Labour (66.6%).

Is there a relationship between a seat’s ‘safeness’ and turnout?

Having looked at marginality and turnout, it’s worth examining whether there is any relationship between the two. Is the propensity to turn out and vote in a particular seat influenced by voters’ perceptions about how safe the seat is?

You might expect that in seats where one party has a large and persistent advantage, voters may be more likely to consider the result a foregone conclusion and thus may be less likely to turn out, whereas closer, more unpredictable contests would be more likely to motivate voters to try and influence the outcome.

In fact, there appears to be little or no relationship between seat safeness and turnout. The chart below shows 2017 election turnout in each seat plotted against the marginality of the result in 2015 and 2017. Seats are spread diffusely across the chart with no discernible pattern linking marginality and turnout percentages.

Persistence of party affiliation in successive elections is also not much of a guide to relative turnout. 418 of the 650 constituencies have been held by the same party at each of the last three General Elections, but the average 2017 turnout in these constituencies (68.5%) is only slightly lower than in the 232 seats that have changed hands at least once in that period (69.3%).

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Image: Polling station by Richard Cracknell