Simpson was also the author of two pieces of historical biography, "The Spanish Marriage" (1933) and "Henry VIII" (1934). "The Happy Housewife", a book of household management, was published in 1934. The "Waiting City", which appeared in 1933, is her translation of a selection from Louis-Sébastien Mercier's "Le Tableau de Paris". Three novels, "Enter Sir John" (1929), "Printer's Devil" (1930) and "Re-enter Sir John" (1932), were written in conjunction with Clemence Dane. "Enter Sir John" was filmed as "Murder!" (1930) directed by Alfred Hitchcock, who later directed the film version of "Under Capricorn" (1949). Helen Simpson also wrote portions of the dialogue for Hitchcock's movie "Sabotage" (1936).