Islands always intrigue, hovering on the horizons of our imaginations – seen, according to your lights, as territories to be taken, ancient redoubts, repositories of secrets, even loci of lands of youth. Where there are no islands, we often imagine them – Plato’s Atlantis, the Celts’ Avalon, the Irish Hy-Brasil, Zeno’s Friseland, Columbus’s Antillia – and occasionally find them, like Terra Australis Incognita, postulated long before Europeans made landfall.