Voters are losing their fear that independence will harm Scotland’s economy, one of the key factors that lay behind the No vote of 2014, according to the latest authoritative survey.

The National Centre for Social Research found more Scots believed leaving the UK would make Scotland’s economy better than those who thought it would make it worse.

In 2014, just 26 per cent of voters thought independence would boost the economy, but that is now 41 per cent, while those saying it would be worse has fallen from 43 to 35 per cent.

The belief that independence would strengthen Scotland’s voice in the world has also risen, from 33 to 49 per cent, over the same period.

The SNP, who start their spring conference in Aberdeen today, hailed the figures as evidence the party was “winning the economic arguments about Scotland’s future”.

SNP business convener and Finance Secretary Derek Mackay also said the research showed an overall majority for independence was “within touching distance” at 48 per cent.

He said: “This survey underlines how confidence in Brexit UK is crumbling - and with people increasingly concerned about what the future holds for Scotland as part of the UK, it is no wonder that people are discussing the immense economic opportunities of independence.”

But the NCSR also found Brexit was a factor in the SNP’s general election losses.

Rather than just a backlash to Nicola Sturgeon’s plan for a second referendum, the SNP suffered because some of its Leave-voting supporters were put off by its strong pro-EU position, while many young Yes supporters switched to Labour under Jeremy Corbyn.

Some Leave-voting SNP supporters also seemed to vote Tory because of Brexit, making the Scottish Tories increasingly Eurosceptic, despite Ruth Davidson backing Remain.

Professor Sir John Curtice, who co-authored the findings, said Brexit and independence were becoming entwined, with Yes supporters increasingly Europhile, and No supporters increasingly Eurosceptic.

Overall, Brexit had not created the boost for independence Ms Sturgeon had hoped for, but nor has it reduced support for leaving the UK, which has changed little since 2014, he said.

Tory MSP Jackson Carlaw said the SNP was meeting this weekend “as a house divided”, with splits over the recent Growth Commission and timing of a second referendum.

“It's clear Nicola Sturgeon is losing her grip,” he said.

Scottish Labour said its activists would spend the weekend campaigning in SNP marginals in anticipation of an early general election.