The SNP’s firm pro-EU stance ahead of the snap general election in June was a significant factor in the party failing to repeat its success at the previous poll in 2015, a report has found.
The EU referendum cut across divisions over Scottish independence and led to a number of those who had previously backed the Nationalists switching their votes to the Conservatives or Labour, according to a post-election analysis by the University of Manchester.
The report found that in the space of three general elections the Scottish party system had been “completely transformed”, with successive referendums on Scottish independence and the UK’s membership of the EU the catalyst.
While nine out of 10 SNP voters in 2015 who backed continued membership of the EU stayed loyal at June’s poll, as many as four out of 10 who supported Brexit looked elsewhere - with Kezia Dugdale and Ruth Davidson’s parties the main beneficiaries.
Although the SNP remained the largest party in Scotland, it lost more than a quarter of its vote share and 21 of the 56 seats it won in 2015.
The Scottish Conservatives, meanwhile, nearly doubled its vote share from 2015, picking up 12 seats, becoming the second largest party in Scotland in the process - the first time it had finished ahead of Labour north of the border since 1959.
Angus Robertson, the leader of the SNP group at Westminster, was among the high-profile casualties at the snap election. His Moray constituency, won by the Tories, returned the largest pro-Brexit vote in Scotland at the 2016 EU vote.
Dr Chris Prosser and Professor Ed Fieldhouse examined how the two referendums interacted to produce the outcome of the 2017 election in Scotland. The authors examined the 2015 to 2017 vote flows amongst four categories of respondents, grouped according to their combination of referendum votes
“Unlike the Yes/Remain SNP voter, Yes/Leave voters were much more likely to defect from the SNP in 2017, with 4 in 10 switching to another party, with similar proportions going to the Conservatives and Labour,” the report said.
“It appears that just as Labour’s position on the independence referendum lost them votes to the SNP, many 2015 SNP voters were driven away by the party’s strong pro-remain stance.”
The report also found that the Scottish Conservatives were gaining ground with No/Remain voters - the largest of the four groups in the Scottish electorate. The group was previously dominated by Labour, but one in five backed Ruth Davidson in 2017.
The report continued: “As a result of picking up a large number of Labour voters, and three in 10 2015 Liberal Democrats, the Conservatives increased their share of this group of voters from two in ten to three in ten between 2015 and 2017.
“Although nationally the Conservatives were more clearly associated with a hard Brexit, the softer approach from the Scottish party, together with a strong position against a second independence referendum and Ruth Davidson’s effective leadership, clearly resonated with this group.”
No/Leave voters were almost evenly split between the Conservatives and Labour in 2015, but in June the Conservatives “picked up nearly half the 2015 Labour voters, six in ten 2015 Liberal Democrats, and the vast majority of 2015 UKIP voters”.
The report added: “Combined this nearly doubled the Conservative share of the vote in this group, with nearly two-thirds voting Conservative in 2017.”
A SNP spokesperson said: “The people of Scotland voted overwhelmingly to remain in the EU, yet a Tory government we didn’t vote for is dragging us out against our will.
“In this year’s election, the SNP won more seats in Scotland than all the other parties put together. By contrast, the Tories stood on a clear platform of a hard Brexit - and voters responded by taking away their majority, and therefore their mandate.
“As each day passes, more and more evidence emerges of the serious threats posed by the Tories’ disastrous plans - that’s why the SNP will continue to stand up for jobs and living standards in Scotland with our proposals to keep Scotland and the UK in the single market.”