Priestley's 'The Good Companions': of its time?

J.B. Priestley’s ‘The Good Companions.’ It is an engaging read. I have recently taken to reading books that are no longer than 190 pages, and preferably much shorter. ‘The Good Companions’ weighs in at 465. To my delight I have been making steady progress, mainly because I have enjoyed the worlds inhabited by the three major protagonists. These worlds are painted in detail and are populated by distinctive and believable characters. These characters are, I assume, the good companions of the title. I have lost myself in their, so far, separate worlds, with the anticipation that they will eventually meet up. It is a style of writing that for many readers has gone out of fashion. Why paint a detailed picture of anywhere when we have already seen picture of them, have travelled there, or can see them on Google maps? But I am won over, or have been until now. I read this book with sympathy for the characters. I am with them as they travel to new adventures. I am in sympathy because I am in sympathy with J.B. Priestley. Everything of his that I have read to date has spoken of generosity of spirit and a respect for the powerless in particular. So, whatever misgivings I have about a character - their apparent shallowness or foolhardiness - I trust that J. B. will deliver in his characters what is expressed by J. B. himself. I have in mind, in particular ‘Postscripts ‘, transcriptions of his radio broadcasts early in the second world war, and published in 1940. But I have hit a dilemma. On two occasions J. B. uses the ’N’ word. It is used in the context of the world of entertainment, where ‘minstrel’ - not without its own problems - might have been used. I could then have dismissed the use of the ’M’ word as being simply a manifestation of  the times, 1929 - the past is a different country. 
Conan Doyle can also be offensive - but Sherlock Holmes is no less popular. I guess in the great scheme of things the use of the ’N’ word on two passing occasions in a 465 page text written 85 years ago is not something to lose sleep about. Maybe my hand wringing says more about me than J.B.