It was the Scots what won it for the Tories, according to new research.
Pollsters Survation have found that Conservative scare tactics about a possible tie-up between Labour and the Scottish National Party (SNP) helped to get David Cameron re-elected Prime Minister.
Survation re-contacted more than 1,700 people it had polled prior to 7 May vote to check how they actually cast their ballot, reports the Scottish Daily Record.
Chief executive Damian Lyons Lowe said: "We know that people were concerned about the SNP. Liberal Democrat and Ukip voters were particularly strong in their view that an SNP-supported Labour government would be 'illegitimate'.
"We believe a significant section of the public were convinced by the polls predicting a hung parliament and so worried about such an outcome that they changed their voting preference to stop it from happening.
"This means that the polls may have been as much a cause of voter behaviour as a measure of it. Clearly, such large discrepancies in the polls are unlikely to be explained by just one factor.
"However, our research suggests that the late swing of voters to the Conservatives and the low turnout among those intending to vote for other parties account for a large part of it."
SNP were a 'gift for the Tories'
Labour's Lord Foulkes told the paper that the research showed the SNP surge and the Tories' threat of a possible Labour tie up had been a "gift" for the Conservatives.
He said the findings were a "brilliant piece of research that shows that the gut instinct of many people about what happened in the general election was right".
He added: "This welcome research shows that many voters turned to the Tories in order to stop the SNP from having any control over the UK government. This is what I mean when I say that the SNP were a gift for the Tories.
"It was not only all the Labour seats they took in Scotland, but also the way they presented the Tories with a campaign strategy that led to them making massive gains in England, particularly in seats previously held by the Lib Dems.
"David Cameron has a lot to thank the SNP for."
SNP: It's all Labour's fault
However, SNP business convener Derek Mackay told the Record: "When the Tories attacked the idea of a Labour/SNP agreement, Labour should have embraced it as a progressive alternative to austerity and pointed out that the Tories were effectively conceding the election.
"Instead, Labour accepted the Tory argument, refused to have anything to do with the SNP and stood up the Tory argument for them.
"In contrast, the SNP pledged to make Scotland's voice heard at Westminster – and that is exactly what our 56 MPs have done every day since."