After the 2010 General Election, of the 59 Scottish seats, the Conservatives have one; Labour has 41 and the Liberal Democrats 11. Were the 2010 election to have taken place without Scotland, the Conservatives would have been the largest party with 305 Commons seats; 9 more than the 296 required for an overall majority (an earlier post looked at seats won in previous elections back to 1945). But in 2010, Labour’s vote share was lower than at any general election since 1945, except 1987. What would happen if Labour’s vote share in 2015 were to recover from this low?

Translating opinion poll findings into the makeup of the House of Commons is difficult enough, but changes in the opinion polls since 2010 suggest that anticipating the results of the 2015 election might be particularly unreliable, for two main reasons:

  • UKIP received 3% of votes in 2010; the latest opinion polls suggest a UKIP vote share significantly higher.
  • The Liberal Democrats had 24% of votes in 2010, higher than at any election since 1945, except that received by the Liberal-SDP Alliance in 1983. Current opinion polls suggest a lower vote share for the Lib-Dems.

Labour’s prospects could be improved by these factors, particularly if it is predominantly Conservative voters moving to UKIP and if those deserting the Liberal Democrats do so more to Labour than the Conservatives.

The following scenarios are based on seat predictions using Electoral Calculus’ ‘standard’ national model. The first shows what might happen if only Labour and the Conservatives see a change in vote share from 2010:Change in Labour and Conservative vote shares

The Conservatives would get an overall majority of seats by gaining 2% point vote share from Labour. Their majority is further consolidated if Scotland is excluded. If the Conservatives lose 2% points, then Labour would be the largest party with Scottish MPs, but the Conservatives would be the largest party without them. In each case neither party has an overall majority.

On the basis of Labour to Conservative vote share change only, Labour has to gain 6% points of Conservative vote share to have an overall majority. Were Labour to do so, it would have an overall majority in the House of Commons with and without Scottish MPs.

But it seems unlikely that the only changes in vote share in 2015 will be between Labour and the Conservatives. If the Liberal Democrat vote share was 15% (which is less than in 2010, but more than their current standing in the polls) with 60% of the residual vote share going to Labour and 40% to the Conservatives, the Conservatives could have 321 Commons seats, just short of the 326 for an overall majority; but they would have an overall majority, 318 seats, if Scottish MPs were excluded.

Liberal Democrat vote share reduced to 15%
(‘RUK’ = ‘rest’ of the UK, excluding Scotland)

Including an increase in UKIP vote share further complicates the prediction. Recent month’s opinion polls have been volatile, at least partly due to the way that different polling companies have been translating their findings for UKIP support into vote share at a general election. An average of the latest polls (from UK Polling Report) puts the party shares at Con 33%, Lab 38%, Lib Dems 10% and UKIP 11%. The Electoral Calculus model translates these into an overall Labour majority, both for the current House of Commons and one excluding Scottish MPs.

Two alternative scenarios are looked at here. In both UKIP get 10% of the vote with three-quarters of the post-2010 increase coming from the Conservatives and the remainder is equally from Labour and the Liberal Democrats. This is roughly in line with the findings from recent polls about the origin of UKIP voters, albeit based on small sample numbers. In the other scenario the Liberal Democrats are assumed to get 15% of the votes and the other the two main parties get their 2010 vote share, less that going to UKIP. Under both these scenarios, Labour is the largest party in the current House of Commons, but the Conservatives are the largest party if Scottish MPs are excluded. In neither case is there an overall majority.

UKIP vote share rises to 10%

If the Conservatives can improve on their 2010 General Election vote share, they look set to be in a majority in the House of Commons, with and without Scottish MPs. Superficially, Labour needs to do more to get an overall majority of both UK and RUK seats. But the fortunes of both Labour and Conservative are partly dependent on the performance of UKIP. In none of the modelled scenarios does UKIP win seats in the House of Commons. But it might prevent either of the two main parties from getting an overall majority (with and without Scottish MPs) and increase the likelihood of a further period of coalition government.

Notes and sources for further information:

Author: Richard Cracknell