If the economy is the deciding factor on September 18 - and the polls show the economic consequences of independence feature far more strongly in Scots' attitudes than issues of national identity - then a new report on the financial prospects after a Yes vote could play a role in making up the minds of the don't-knows.

The report by Fathom Consulting, a consultancy working for business, banks and governments, concludes an independent Scotland would be as financially fragile as Greece unless three main factors came to pass: first, Scotland could largely get rid of its banking assets, or liabilities as they are now; second, it could establish its own currency; and third, it had at least a 90 per cent share of UK oil revenues. If these factors were not in place, says the report, Scotland would face a situation worse than the one in Greece.

There will be some who see any comparison to Greece as scare-mongering, but there are hard questions about the costs of independence and Fathom's report focuses on three of them.

Loading article content

The first concerns the banks and the scale of Scotland's liability for them. John Swinney, the Finance Secretary, has said Scotland would take on a share of the weight of failed banks, but Fathom's report says that, for the Scottish economy to be viable after a Yes vote, the country would have to get rid of the majority of banking assets.

The scale of the liability is large: as it stands, Scotland's banking assets are more than 1,000 per cent of GDP, much bigger than countries that were bankrupted during the recession. But a spokesman for Alex Salmond points out that financial services account for a lower share of the economy of Scotland compared to the UK's. It is also possible that Scotland would end up with liability for a much smaller sector. RBS, for instance, might have to leave Scotland due to European rules that dictate a bank must be based where most of its customers are.

The second issue in the Fathom report is oil and gas, which remains one of the most troubling questions for an independent Scotland. Fathom says Scotland would have to be allocated the vast majority of UK North Sea oil. That might happen in any deal with the UK, but Better Together relies on projections that revenues from oil and gas will decline. The alternative view is that there have been high levels of investment in the Scottish industry in recent years and Mr Swinney believes the outlook remains strong.

The final central issue in the report - currency - also lacks clarity. Fathom says an independent currency would be essential to allow Scotland to respond to changes in the oil price, but the chance of such a separate currency happening is another of the uncertainties: the SNP says Scotland will share the pound; the Westminster parties say it won't.

These uncertainties are frustrating for voters, but the conflicting economic forecasts are central to the debate and Fathom's report has to be seen as a forecast like any other. Voters may well put the economic questions at the heart of their decision, but the question is which of the answers to believe.