John Appleby came into being during a sea voyage from Liverpool to Adelaide. Ocean travel was a leisured affair in those days, and the route by the Cape of Good Hope took six weeks to cover. By that time I had completed a novel called Death at the President's Lodging (Seven Suspects in the U.S.A.) in which a youngish inspector from Scotland Yard solves the mystery of the murder of Dr. Umpleby, the president of one of the constituent colleges of Oxford University. It is an immensely complicated murder, and Appleby is kept so busy getting it straight that he has very little leisure to exhibit himself to us in any point of character or origins. But these, in so far as they are apparent, derive, I am sure, from other people's detective stories. I was simply writing a yarn to beguile a somewhat tedious experience...