In September 2014 there will be a referendum in Scotland about whether to leave the United Kingdom, and if Scotland votes yes that will signal the end of a 300 year union. How has it come to this, what would Scottish independence mean, and what’s going to happen? Jim Gallagher, Gwilym Gibbon research fellow at Nuffield College, Oxford, examines the potential consequences of a ‘yes’ vote both for an independent Scotland and the rest of the UK.