Eddie Barnes: Chancellor pins hopes on "unlikely" fiscal union should Scotland vote to quit UK AT 105 pages long, the UK government's paper on currency and monetary policy, published yesterday, is a meaty document, but if there is one word that George Osborne would like the entire thing to be distilled down to, that word is "unlikely." It is "unlikely," declared the Chancellor yesterday, that - post-independence - there would be a formal London-Edinburgh deal, to share the pound and maintain a stable currency union. "Is it really worth it?" he pondered yesterday, as he assessed the risks that such a deal would create for the "continuing UK." The prospect of that country politely but firmly telling Scotland "thanks, but no thanks" to a currency-sharing deal after a "Yes" vote is one that the pro-UK side would very much like people to consider over the next 18 months. Research conducted by Better Together chiefs is understood to show that the question of the currency is one of the top three main issue of concern for voters as they weigh up the choice. If people aren't clear about what will happen to it prior to next September, then they will not take the plunge; after all, note pro-UK campaigners, a don't-know is a vote-no. In a sign of how seriously the SNP treats this latest attack, the trio of Salmond, Sturgeon and Swinney all took to the air-waves yesterday to rebut Mr Osborne's call. Not only would the UK want to keep Scotland in a new currency zone, goes the argument, Scotland would still be able to exercise complete freedom over taxation and spending. As the trio spread reassurance across the air-waves, one can only speculate as to their thoughts about Green MSP Patrick Harvie as he continued to insist that the option of a new separate Scottish currency should be left open. The battle lines between the two sides on the currency are thus drawn. As usual, the truth is located somewhere in the middle. It is hard to conceive the "continuing UK" not negotiating with Scotland after a Yes vote. History, geography and trade all point towards it. Rather, and as with the row over Scotland's European Union status after a Yes vote, the real question mark is over the terms of that deal. Arguably, here the Treasury's critique is on stronger ground. London would want the power to be able to intervene if Scotland's fiscal plans put the stability of the new zone at risk, the paper claimed yesterday. Any Scottish effort to cut taxes (for example, on corporations) could be vetoed to prevent an erosion of the currency zone's tax base. Similar points have already been made by unbiased economists and analysts. It all prompted Chief Secretary to the Treasury Danny Alexander yesterday to claim that even the extra powers proposed by the new Scotland Act may be greater than those that Scotland would get after negotiations. That will be greeted with scorn by the SNP, but the wider point about the constraints that a potential deal with the UK would impose will not be so easy to dismiss.