THE SNP have received a boost heading in to next year's Holyrood vote after it emerged that it retains the support of an overwhelming majority of those who helped the party to its general election landslide.

A new poll for TNS found that 97 per cent of SNP voters in May intend to support the party again with their constituency vote in the Scottish Parliament election in 10 months time.

Meanwhile, 15 per cent of Labour voters two months ago said they would back another party, with more than half of them now intending to vote SNP. Among other parties 16 per cent of Tory voters and more than a fifth of those who backed the Liberal Democrats are likely to change sides.

SNP Business Convener Derek Mackay MSP said: "This is another very encouraging poll for the SNP showing extraordinary levels of support for the party after more than eight years in government – and is a vote of confidence in the strong start that the new SNP MPs have made in standing up for Scotland’s interests at Westminster."

The poll of more than 1,000 adults also asked voters about important issues to them when deciding on which party to support. Nearly six in ten pinpointed healthcare, with education, job prospects and the economy also featuring prominently.

Despite the possibility of Nicola Sturgeon using the election to seek a mandate for another referendum, fewer than one in five highlighted the issue of independence. More voters - 22 per cent - pinpointed immigration despite Holyrood having no direct control in the area.

In terms of the constituency section of the vote, the SNP received 60 per cent support, unchanged from a month ago. Labour increased one point to 20 per cent, with the Tories down one to 14 per cent. The Liberal trailed on five per cent, although the total was two per cent higher than last month.

In the regional list section, which sees voters back a party rather than an individual and seats allocated to make the overall result more proportional, the SNP led with 51 per cent, compared to Labour's 21 per cent. There were disappointing results for the Scottish Greens, with the party, hoping to make a major breakthrough next year, seeing support fall to seven per cent - down three points.

If the result is repeated next May, it would see the SNP win another majority with 75 MSPs, according to PR firm Weber Shandwick's simulator. Labour would be left with 27 and fail to win a single constituency, with the Tories and LibDems unchanged on 15 and five seats respectively. The Greens would have seven MSPs, up from two currently, meaning nearly two thirds of Holyrood politicians would belong to pro-independence parties.

Tom Costley, head of TNS Scotland, said: "As would have been expected, political opinion in Scotland appears to be quite stable, with the SNP in a commanding lead over the other parties. Our survey also suggests that the SNP vote may be holding together more strongly than the Labour vote.

"However, given that Labour is still in the process of choosing new UK and Scottish leaders, the picture may change later in the year when the leaders of all the parties set out their stalls at their autumn conferences.

"It is worth noting that the SNP lead among younger voters continues to be especially strong – 73 percent of those aged 16-34 who express a party preference say they intend to vote SNP, against 12 per cent backing Labour."

The results of the survey came as academics suggested that turnout may have been a key factor in why pollsters called this year's general election inaccurately. In the run up to the vote, a hung parliament was consistently predicted as a near-certainty, before the Tories won a shock majority.

The British Election Study said that data from its online survey of 30,000 people conducted after the election strongly show that many respondents said they intended to vote but then did not. These were most likely to be Labour supporters.

Researcher Dr Jon Mellon said: "Our data show the Labour lead among unlikely voters grew hugely between 2010 and 2015, suggesting differential turnout is an important factor in explaining the polling miss.

"If differential turnout is indeed the primary cause, then this is good news for pollsters as it should be possible to fix the problem using turnout weighting that accounts for the wider set of factors we identify."

The survey also suggests some respondents are lying to pollsters both before and after the election. The data shows in areas where local elections did not take place in 2015, 20 per cent of respondents claimed to have voted in them.

Between three and six per cent of respondents claim to have voted by post before the postal ballots were actually issued. And 46 per cent of respondents who were not registered to vote in June 2014 claimed to have voted in the 2014 European Elections.