The number of voters in Northern Ireland backing Irish unity has trended higher in recent years. A Queen’s University survey put the level of support at 36 per cent while a Belfast Telegraph poll put the figure at 41 per cent. Nowhere near an overall majority, of course, but high enough for politicians and journalists to wonder about the when and the how.  It may be decades away, but for many commentators, unity of some sort now seems like a real possibility. It has provoked any number of speculative commentaries teasing out cost, culture, and implementation. And if constitutions are…