On their return to England, Sykes and Byron wrote a novel together under the name of Richard Waughburton, "Innocence and Design", published in 1935. A little later, Sykes and Cyril Connolly planned a book with the title of "The Little Voice". In common with other projects of Connolly's, the book never got beyond the planning stages. Sykes published in 1936 a biography of the German Persianist Wilhelm Wassmus; he did not, during later years, include this volume in his list of his publications. A memoir of Byron, killed at sea in 1941, was included in Sykes' best-selling book, "Four Studies in Loyalty".