Away from government

How close were Labour from forming a government in 2017?

The 2017 General Election ended in a hung parliament: the Conservatives won 317 seats. Several articles claimed Labour were 2,227 votes away from the chance of government.

That statistic has enjoyed a recent renaissance on social media. Guardian columnist Owen Jones asserted:

Labour came within 2,227 votes and seven constituencies of forming a government in 2017.

This article examines the claim. The original analysis miscalculated or misstated the figure, relying on adamant assumptions.

What ‘2,227 votes’ means

In the 2017 General Election, the Conservatives had 13.6m votes and 317 seats. Labour received 12.9m votes and 262 seats. Since the Conservative seat total was less than 326: it was a hung parliament.

In Great Britain, the Conservatives won a vote share of 43.4%, up 5.8 points on 2015. For Labour, their vote share was 41.0% — an increase of 9.8 points from the 2015 election.

In a UK General Election, each constituency is a separate election. The voting system elects whichever candidate wins the most votes. This is often called First Past the Post.

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Labour came second in 301 constituencies. (Image: ggplot2)

Some constituencies are marginal. It is close between the winner and which candidate came in second. In 2017, the most marginal constituency was North East Fife. Stephen Gethins (SNP) won this seat by two votes.

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2,227 is the sum of the seven smallest majorities in Conservative seats where Labour were second. The figure should be either:

  • Switched votes: the number of votes that Labour need to switch from the Conservatives (1,118).
  • Added votes: the number of votes that Labour needs to add (2,234).

In each case, Labour won these seven constituencies by minimal votes. That hypothetical Commons would have the Conservatives on 310 seats. Here, Labour would have 270 seats. The DUP had 10 seats. The Conservative seats would leave the Conservative-DUP grouping beneath a working majority.

The assumptions behind this claim are:

  • The switched or added votes occur only in those specific seven constituencies.
  • No other votes in any other constituencies change.
  • The Conservatives do not form a minority government, or find arrangements.
  • The hypothetical Commons does not call another election.
  • Labour form an agreement with other parties to make a minority government.

This is a hypothetical scenario. News articles state Jeremy Corbyn had “the chance” and “could have formed” a government. It is not an inevitability.

The other side

We can do a similar calculation for the Conservatives, looking at their second places.

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This is a histogram, according to the size of the majority. (Image: ggplot2)

The party needed only 50 switched votes to reach 321 seats. That would be a working majority.

528 votes would need to switch for the Conservatives to win 326 — a Commons majority. These figures represent the smallest number of switched votes.

We could also calculate what vote share would need to switch across the country. Constituencies are not independent events.

How big does a uniform national swing need to be? We assume: if one party increased their vote share, that same change happens in every seat. Only switching between Labour and the Conservatives occurs. Turnout does not change.

These values are uniform swings in Great Britain. 0.04 points from Labour to the Conservatives gives the Conservatives 321 seats. 0.37 points in the other direction reduces the Conservatives to 310 seats.

The two switched vote shares are equal to around 13,000 and 116,000 votes across Great Britain. Since vote share changes, these figures are indicative and not precise estimates.

The Conservatives needed fewer switched votes than Labour for those close outcomes.

Hypothetical

The statistics derive from simple hypothetical scenarios. Under First Past the Post, small changes in votes can have large ramifications. Some constituencies are marginal.

If Labour were closer to the Conservatives in votes, electoral dynamics also change. In this alternate universe, the messages and targeted campaigns could have been dissimilar. Parliament may not have called the election.

The ‘2,227 votes’ figure appears to be a miscalculation. Suggesting Labour were a thousand votes from “forming a government” needs severe clarification. It relies on diamond-strong assumptions.

This blog looks at the use of statistics in Britain and beyond. It is written by RSS Statistical Ambassador and Chartered Statistician @anthonybmasters.

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