"As things stand, the 1.8 million population of Northern Ireland is preventing the rest of the UK from leaving on the most favourable terms for both the UK and the EU27 ... And the other 64 million people in the UK should not have their futures determined by a recalcitrant minority party with a mere 10 MPs." So writes the author and broadcaster David Green in an article in the Spectator in which he suggests that the time may have come for a referendum on Irish unity as the solution to the UK's current Brexit impasse. We speak to David Green and Nelson McCausland.