Under the Geneva Convention’s “median line” rules on national boundaries, Scotland would take control of 90pc of the gas and oilfields currently under UK jurisdiction. If oil revenue is allocated along these lines and revenue trends seen between 2005 and 2010 continue, an independent Scotland would have a fiscal balance close to that seen for the UK as a whole. In 2009/10 it was -11.1pc of GDP for the entire UK, and -10.6pc of GDP for Scotland.