SENIOR Tory, Labour and LibDem politicians have told the author of a new economic blueprint for independence that the document has made the Yes case stronger.

Andrew Wilson, the chair of the SNP’s Sustainable Growth Commission, said politicians across the spectrum – including from the three main Unionist parties – had privately conceded to him that his work had strengthened the independence cause.

READ OUR EXCLUSIVE IN-DEPTH INTERVIEW WITH ANDREW WILSON:​ Growth Report author says independence case is 'far more credible' than others

The economist and former MSP gave an exclusive detailed interview to The National after a barrage of criticism of his findings this week from a number of people on the left of the Yes movement.

He said: “I have received feedback from across the political spectrum – from people in Labour, the Conservatives and the LibDems, as well as figures from outside of politics, from people who are opposed to independence, saying ‘I will always oppose what you are saying publicly. But privately I believe you have strengthened the cause of independence’.”

READ MORE: Nicola Sturgeon responds to Growth Commission criticism

Wilson said the pro-Union politicians were a mix of parliamentarians and senior figures in the parties. He would not name them, however...

His report has been under fire by critics on the left this week, who challenged his recommendation that an independent Scotland should keep using the pound without being in a currency union with the UK.

Most critics wanted an independent Scotland to move swiftly to adopt a Scottish pound. Some argued he had advanced an austerity agenda.

Responding, he said the commission had spent months assessing whether to back a new Scottish currency, before electing to carry on using sterling with the option to transfer to a new currency once six key economic tests were met.

He added voters on the door step would reject independence if they couldn’t carry on using the pound amid fears over a new currency’s stability in the early days of independence. “I would suggest those who want to get to a Scottish currency and not doing it with an orderly transition and not planning that orderly transition upfront makes it less likely that we will ever win – and more likely that people will see problems in the prospectus,” he said, citing voters fears over their savings and mortgages and the possibility people could take their money out of the new state.

READ MORE: Common Weal rejects Growth Report call to keep pound sterling

On the austerity claims, he hit back: “People on the pro-independence side need to think carefully about what the are saying because they are basically providing an echo for a Labour party attack ... What we set out is an absolute opposition to austerity. If the model we have suggested for reducing the deficit was applied to the last 10 years we would have eliminated the Tory austerity cuts to the Scottish budget. It locks in public spending growth ahead of inflation across the cycle. What is the alternative? The idea that someone will give you money for nothing is for the birds. It’s not credible.”

Scottish Labour’s Jackie Baillie said: “This is delusional from Andrew Wilson. His cuts commission proposes another decade of severe austerity for Scotland.”

A Tory spokesman said: “Even hardcore nationalists can’t stomach this independence blueprint. The idea that Unionist parties would be in favour of it is sheer fantasy.”