With the SNP's best-known business supporters notable by their absence from last week's Yes Scotland launch, a key issue for the campaign is whether business leaders who backed Alex Salmond in last year's Holyrood election will be prepared to vote for independence.

The SNP's narrow win in 2007 followed careful cultivation of the business community and publication of a list of 100 business supporters. One of the most prominent, Sir Tom Farmer, multi-millionaire founder of the Kwik-Fit chain, has now said that he does not support independence but favours more powers for the Scottish Parliament. Other high-profile SNP business supporters missing from the Yes Scotland line-up were Sir Brian Souter, the co-founder of Stagecoach who has contributed around £1 million to the party, Sir Tom Hunter and Jim McColl of Clyde Blowers, who has also previously championed fiscal but not political independence.

The most noteworthy endorsement for the SNP before last May's election came from Sir David Murray, a committed Unionist who had supported the Conservatives at the 2010 General Election. His dramatic turnaround supporting greater fiscal powers for Scotland was accompanied by a statement that he remained in favour of the Union. This stance of backing Mr Salmond as an able First Minister while remaining opposed to his party's defining principle of independence can be viewed as a short-term strategy. Nevertheless, as pragmatists who recognise the necessity of dealing with whichever party is in power, several entrepreneurs shared the view that the SNP, having demonstrated competence in Government, deserved another term in office. In some cases that support cooled with the announcement of a "supermarket tax" on large retailers, which did not go down well in the boardrooms of major companies. The prospect of lower corporation tax is obviously favoured by business but with most of Scotland's trade being with the rest of the UK, there is concern about losing the advantages of a single market.

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If Sir Tom Farmer's support for maximum devolution, or full fiscal autonomy short of independence, is widely shared among business people, it would strengthen the case for including that option in the referendum. Opinion polls point to popular support for further devolution of fiscal powers, which presents something of a conundrum for the Nationalists. Do they seek to include devo-max as a second question, knowing that it would probably be more popular with the "imponderables" than independence?

The timescale means there can be no excuse for not engaging with the pros and cons of the full range of fiscal possibilities. It is an opportunity that should be seized.

The Yes campaign launch may have emphasised the feel-good factor by showcasing actors and singers but the last two Scottish Parliament elections have demonstrated, regardless of the emotional appeal of independence, Scots, particularly the business community, are most concerned about the economic implications of a yes vote.