Dewar (left) launches 'yes yes' campaign

Dewar Rejects Devolution Tax Warning

Mr Dewar's comments follow a warning last week from Sir Bruce Pattullo, the Governor of the Bank of Scotland, that an Edinburgh parliament with tax-varying powers could leave voters up to £6 a week worse off.

"What we are doing is giving very limited tax varying powers, and it's a matter for a grown-up Parliament with grown-up responsibilities to decide how it will use these powers," said Mr Dewar.

"What Sir Bruce is doing is assuming, as the Conservatives tend to do, that that power will be used to the maximum as a matter of routine, almost, and therefore they produce some fearsome figures. It's not justified," he insisted.

Pattullo: Warning of 'Tartan tax'

"I actually believe it amounts to saying that you can't trust Scots to act responsibly if you put them in positions of authority over their own affairs," he told the BBC Radio 4 programme The World This Weekend.

For his part the SNP leader Alex Salmond welcomed a call for a double yes vote from James Scott, a past executive director of Scottish Financial Enterprise.

"James Scott's call for a yes-yes vote on September 11 is a major contribution to the referendum campaign," said Mr Salmond.

"Last week we had the bizarre spectacle of Bruce Pattullo launching a yes-no campaign on behalf of the Bank of Scotland, an absurd and inappropriate initiative which failed to get the endorsement of a single Scottish business figure," added Mr Salmond.

The devolution campaign received a boost when the actor Sean Connery gave his unequivocal support to devolution.

"It's yes, yes, yes for me," said Mr Connery, describing the coming referendum was an "opportunity that should not be missed."

"I think it has teeth and in my own opinion it's the next step from independence," said the film star.

"But you know to run it, they've been out of circulation for 300 years, so you're going to get a quick learning process. But the value we have is that we can learn from the other parliamentary mistakes," he said.