Salmond says sterling-zone would work Alex Salmond insists an independent Scotland could cohabit happily with the rest of the UK in a monetary union as the debate on his homeland's future switched from haggling over a referendum to hard economics. Scotland's First Minister was fielding questions on what he called a "historic day" after he and David Cameron signed an agreement in Edinburgh to give Scots a straight yes-no vote on independence in 2014. Mr Salmond, the Scottish National Party leader, said the referendum was "the most important political decision in 300 years" of Scottish history, since the Act of Union in 1707. But the ink was barely dry on the "Edinburgh agreement" before he was challenged on his claim that Scotland could be more "prosperous and successful" outside the union. In particular he was challenged on whether he was in danger of replicating the tensions and instability in the eurozone by proposing that an independent Scotland share the pound with the rest of the UK. "The problem with the comparison is the different productivity in the areas of the eurozone," he said, arguing that - unlike Greece and Germany - Scotland and England had similar economic profiles. "It's the difference between an optimal currency area and one that is clearly not optimal," he said. Mr Salmond had previously wanted Scotland to join the euro, but favours sticking with the pound for now. Mr Salmond would hope to have a Scottish representative on the Bank of England's monetary policy committee setting interest rates across the "sterling area" but concedes that London may require a fiscal agreement, too - a model that erodes national sovereignty in the eurozone. However he insisted Scotland's fiscal position was better than that of the rest of the UK - a claim largely dependent on the distribution of North Sea oil revenues - and said London need not worry about budget decisions in Edinburgh. "In terms of the current fiscal position in Scotland, there's a level of comfort which should give a margin of manoeuvrability," he said. He believes Scotland could afford to spend more on infrastructure. Those claims will be tested over two years by pro-union campaigners, led by Alistair Darling, former Labour chancellor, and by business leaders looking for assurances that independence would not harm Scotland's investment climate. Mr Salmond has chosen a year for the referendum that marks the 700th anniversary of the English defeat by the Scots at the battle of Bannockburn, but he will need more than political symbolism to secure victory. Some opinion polls suggest opposition to independence in Scotland is running at about 2:1. Mr Salmond, asked whether the referendum deal was a political death warrant, said: "I believe we will win." Mr Cameron tried to take the drama out of the signing ceremony, leaving Edinburgh without holding a press conference but pleased that he had secured his main objective: ensuring just one question appears on the referendum ballot paper. Mr Cameron said the straight choice on independence would produce a "fair, legal and decisive" outcome in the referendum. Mr Salmond had mooted the idea of an extra question, asking whether Scots wanted more fiscal powers devolved to Holyrood. However Mr Salmond did secure his choice of date for the poll and an extension of the franchise to 16- and 17-year-olds, whom are deemed more likely to support independence.