And, finally, they assume that North Sea oil will cushion the Government’s expenditures, even though these revenues have been falling for years. All credible independent forecasts are that they will continue to do so. Updated figures due to be published this week by HMRC, show such income sinking to as little as £4.7bn in 2013-14, from £6.1bn in 2012-13 and £11.1bn the year before. Admittedly, these falls are partially due to relatively high investment expenditure by producers, which creates jobs and other forms of tax revenue. But the long-term direction of travel is clear. According to the Institute for Fiscal Studies, an “independent Scotland would face unsustainably [high] levels of public sector debt over the next 50 years unless further tax increases or spending cuts were announced”.