In his recent visit to Goldsmiths, University of London, Alan Bennett, the playwright and author shared a favourite anecdote about Alan Walker Tyson, the late Oxford musicologist. Tyson, notorious for an almost pathological love of puns, was listening to a vegetarian colleague at All Souls College outline his plans for a forthcoming dinner. "It will begin with a Jerusalem artichoke soup," the don explained, "and then I think we will have a Jerusalem artichoke salad." Tyson seized the opportunity to inject some sanity in the developing menu. "Surely, only once in Royal David's city?" he interjected.