Adrian Kavanagh, 10th May 2015

Thursday’s general election in the United Kingdom produced a victory for the Conservative Party, as well as for the Scottish Nationalist Party in Scotland, but brought about a stunning defeat for the junior partners in the outgoing government, the Liberal Democrats, while Labour lost ground, most notably in Scotland. The United Kingdom Independence Party emerged as the third largest party in terms of vote share, winning more than one eight of all the votes cast, but ended up winning just one seat. The Green Party quadrupled their share of the vote relative to 2010, but these vote gains did not translate into seat gains. 

The degree to which vote share at this election was translated into seat numbers shows that the UK first-past-the-post electoral system is biased in favour of two larger parties, but also to some degree biased in favour of the regional parties, such as the Scottish Nationalist Party and the parties in Northern Ireland. This electoral system, by contrast, is biased against smaller parties which have geographically diffuse support bases, such as the Greens, UKIP, and the Liberal Democrats.

• The Conservatives won 50.9% of House of Commons seats with 36.9% of the UK first preference votes.
• The Labour Party won 35.7% of House of Commons seats with 30.4% of the UK first preference votes.
• The Scottish Nationalist Party won 8.6% of House of Commons seats with 4.7% of the UK first preference votes.
• The Democratic Unionist Party won 1.2% of House of Commons seats with 0.6% of the UK first preference votes.
• The Liberal Democrats won 1.2% of House of Commons seats with 7.9% of he UK first preference votes.
• Sinn Fein won 0.6% of House of Commons seats with 0.6% of the UK first preference votes.
• The Social and Democratic Labour Party won 0.5% of House of Commons seats with 0.3% of the UK first preference votes.
• Plaid Cymru won 0.5% of House of Commons seats with 0.6% of the UK first preference votes.
• The Green Party won 0.15% of House of Commons seats with 3.8% of the UK first preference votes.
• The United Kingdom Independence Party won 0.15% of House of Commons seats with 12.6% of the UK first preference vote.
• The Alliance Party were the largest party (in terms of vote numbers) in UK to fail to win a seat, winning 0.2% of the UK first preference vote.

Nearly one quarter of all the votes cast in this election were won by UKIP, the Liberal Democrats and the Greens (24.3%), but between them these parties only accounted for 10 seats in the House of Commons (1.5%). The Green Party won the exact same vote share as the Irish Green Party did in the 2002 General Election. The Irish Greens, however, were able to translate this vote share into 6 seats in Dail Eireann (3.6% of the seats), thanks to the Proportional Representation by Single Transferable Vote electoral system.

The combined vote share for the Conservatives (41.0%) and Labour (31.6%) in England was 72.6%, but these parties accounted for all, but eight, of the 533 seats being contested there (98.5%). With 30.00% swing to the party there, the SNP won 50.0% of the vote in Scotland, but won 56 of the 59 seats (94.9%). Labour were down 17.7% to 24.3%, but lost all but one of the 41 seats they had won in Scotland in 2010, leaving them with just 1.7% of the Scottish seats. The Liberal Democrats were down by 11.3% in Scotland and won 7.5% of the vote there.  They lost all but one of the 11 seats they had won in Scotland in 2010, leaving them with just 1.7% of the Scottish seats.

There has been much emphasis on how the opinion polls got it wrong at this election. In reality, the opinion polls were not especially out of kilter with the actual election result. If the figures in the BBC Poll of Polls for 6th May are compared with the actual election figures, it can be seen that the support estimates for the United Kingdom Independence Party (13%), the Liberal Democrats (8%) and the Green Party (5%) were remarkably close to those parties’ vote share in the actual election. This could be viewed as being somewhat surprising, given the expectation that some supporters of these smaller parties might have switched their vote tactically to one of the two larger parties just ahead of the election to prevent their vote being wasted.  The big difference related to the support estimates for the two larger parties. The Conservatives won a 2.9% larger vote share in the actual election than had been predicted in the BBC Poll of Polls (34%), while the Labour vote share (33%) in this poll of polls was over-estimated by 2.6% when contrasted with that party’s share of the vote in the actual election. What proved particularly problematic in relation to these polls was the manner in which the poll figures got translates into seat estimates, as well as, of course, the degree to which the first past the post system inflates seat levels for the larger parties.

Other aspects of my take on the opinion polls and the impact of the electoral system can be viewed in the interview I did with Sinead O’Carroll of the thejournal.ie yesterday, as linked here. John Curtice of Strathclyde University offers a more in-depth account of the opinion polls and the general support trends evident in Thursday’s elections in today’s edition of The Independent, which is very much worth reading.