Whenever the matter came up, Marsh said that she did not follow Sayers in falling in love with her detective. I think that she did. Or at any rate, she identified with Alleyn’s wife: “People who know me very well see me in her. Agatha Troy’s tastes are mine and of course she’s a painter and I started off as a painter.” And viewing Alleyn through Troy’s eyes made him much less the effete aristocrat that he often seemed to be in the early novels. By the time that Marsh brought him to New Zealand to help the local authorities in Colour Scheme (1943) and Died in the Wool (1945), Alleyn has gained sensitivity and sympathy. Though he may have emerged from Lord Peter Wimsey, he had become the spiritual ancestor of Ruth Rendell’s Wexford and P. D. James’s Dalgliesh.

The fact that Alleyn is a policeman has led some scholars to write that “in most cases he relies on routine police procedure.” In fact, although Alleyn has fingerprint experts and photographers who investigate the scene of the crime, technical matters are rarely described and the solutions are almost never discovered by such means. Marsh’s books are part of the Golden Age tradition, in which crimes are solved by clues given to the reader and the murders are frequently bizarre. In Marsh’s books, bodies are hidden in bales of wool, and victims are dispatched by guns lurking inside pianos, by lethal wine bottles, and by poisoned darts. Although not particularly interested in the form of detective fiction, she nonetheless followed it almost religiously. She explained that “the mechanics in a detective novel may be shamelessly contrived but the writing need not be so nor, with one exception, need the characterisation. About the guilty person, of course, endless duplicity is practised.” In 1981, I wrote to Ngaio Marsh about research I was doing into the life of another mystery novelist. I received a friendly letter in which—as an aside—she mentioned that “at the moment I am deeply involved with a very elaborate case that I have funked until now.