From 1915 to 1920 he worked as an assistant to Gardiner, primarily in the lexicographical work which led to the 1947 publication of "Ancient Egyptian Onomastica." Of this period, Gardiner said: "He was a real Bohemian and much of his research was carried on in his own lodgings at dead of night." A series of articles written while working with Gardiner led to the publication, in 1924, of his major publication, "Studies in Egyptian Syntax." In this book, he identified the unusual syntactical relationship between negation and tense, now known as Gunn's Rule. Gunn's Rule still appears in modern textbooks.