having got used to the slightly 1930s style you are introduced to a writer clearly familiar enough with the detective story format to have a bit of fun with it. references to Sherlock Holmes make it clear that Milne knows what he is talking about.
But rather than use the Christie approach of a well known detective figure entering the scene Milne introduces a character that has been drifting round not quite sure what to do with his life.
Anthony Gillingham has an uncanny ability to remember details of things he has casually seen and an enquiring mind. as a result it is he, not the police, that starts to uncover the mystery behind the death of the red House owner's brother.
But can he work it out completely? Time will tell...