If the UK leaves the EU, what happens on the island of Ireland? Its people would be living on either side of an EU border. In this edition of BBC Radio 4’s Analysis, Edward Stourton explores an aspect of the Brexit debate that few elsewhere in the UK may have thought about, but which raises urgent questions. Would there be a new opportunities, with a new version of the old Anglo–Irish special relationship? Or could a divisive border and economic harm revive dangerous tensions?