Fletcher is a somewhat forgotten author from the classic age of detctive fiction many of whose books are well worth reading. However, this isn't one of them. It's difficult to explain why without spoiling the plot, but I think it's fair to say that there are various developments, seemingly quite important at the time, which are left completely unexplained at the end, not the least of which involve the title and those named in it.
The sensibilities in the book are of their time, but in this instance are less to do with race (although the Scots come in for a little sideswipe about their supposed love of money and, being from Halifax, Fletcher's Yorkshiremen are always cleverer than everyone else) than to do with the place of women. One lady isn't sure how to respond appropriately to the police until her husband returns home. 'But, being a man, he knew that it was every citizen's duty to assist the police, and he accepted his fate cheerfully, and bade his wife give the gentlemen every help that lay in her power.'