JOHN Swinney has been ordered to reappear before a Holyrood committee, after leading academics cited by the finance secretary in the SNP's case for fiscal autonomy were unable to back up their claims that it would boost Scotland's economy.
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The SNP government has relied heavily on a report from professors Andrew Hughes Hallett and Drew Scott over a claim that financial independence would lead to an increase of up to 1.3 per cent in Scotland's GDP.
But the claim - widely seen as a key argument for move towards Scottish independence - was challenged yesterday during a hearing of Holyrood's Scotland Bill committee.
During a bad-tempered clash, the academics distanced themselves from SNP claims that their report provided a case for fiscal autonomy.
One of the professors threatened to walk out, while a prominent SNP MSP said the professors had been treated "shabbily" and he was "ashamed" to be a part of the group.
The row erupted as the professors were grilled by MSPs over the claim in a report they authored that Scotland's GDP would rise by between 0.6 per cent and 1.3 per cent if Holyrood was handed full economic powers.
First Minister Alex Salmond referred to the report during his speech at last year's autumn SNP conference, when he said: "We know, thanks to the work of Andrew Hughes Hallett and Drew Scott, that with economic powers we could grow the Scottish economy by an extra 1 per cent a year."
Mr Swinney also told a previous hearing of the Scotland Bill committee that he backed the report "undertaken independent of the government by Prof Hughes Hallett and Prof Scott, which demonstrated the implications of fiscal responsibility".
During yesterday's committee hearing, convener Labour MSP Wendy Alexander demanded to know "the source of the analysis" used by the two academics. The former Scottish Labour leader said there was "no robust evidence" to back up the claims.
Prof Scott said he and his colleague were attending the hearing to give evidence about the UK government proposals to increase Holyrood's powers through the Scotland Bill. When asked about fiscal independence, Prof Scott, from Edinburgh University's European Union Studies department, said: "It strikes me we should simply leave if all we're going to do is discuss this."
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Prof Hughes Hallett, of St Andrews University, said the claims about increasing GDP were "referenced in the papers" he and his colleague had written, but was unable to say what the evidence was or where it came from. He said: "Increased powers could be expected to increase the level of GDP by between 0.6 per cent and 1.3 per cent."
Prof Scott told the committee: "If you would like us to conduct a seminar on our work, then we could probably do that in a more convivial atmosphere."
He added: "We're here today to provide evidence on the impact of the Scotland Bill, not to discuss, through academic, intellectual arguments, an alternative that is not being legislated."
Tory committee member David McLetchie said Ms Alexander's line of questioning over fiscal powers was "reasonable".
But Prof Scott replied: "I'm not responsible for the use the Scottish Government makes of our work."
After the point was put to him again, Prof Scott said: "It strikes me we should simply leave if all we're going to do is discuss this."
Meanwhile, deputy convener, SNP MSP Brian Adam, said: "We've treated these two witnesses shabbily, and personally I would like to apologise for the way you've been treated."
However, his Labour committee colleague Peter Peacock later said the finance secretary would be recalled to justify the Scottish Government's use of the academics' evidence to back full financial independence.