In addition to his editorial duties, Greig has literary interests, for instance writing the foreword for the "Forward Book of Poetry" (1999). His 2011 book, "The Kingmaker" is about his grandfather, Louis Greig, a war hero and rugby international, who became mentor, physician and friend to the young and hesitant Prince Albert, the future King George VI. His influence helped to guide the prince from a stammering, shy schoolboy to become the monarch who saw Britain through the Second World War.