"... rather than in the grim purlieus of the Lambeth waterside."
-- S. Winchester, The Professor and the Madman, page 175.
Neighborhood or environs are the suggested dictionary definitions for purlieus; the word origin suggests an area within walking distance. What possible reason might the the author have to use purlieus, rather than neighborhoods, environs, alleys, streets, thoroughfares, recesses, sidestreets, byways, blocks, slums, surroundings, paths, walks, roads, mazes, spaces, grottos, or any number of other English-language words with which more readers might be familiar? My personal supposition, as you, dear reader, may have by this point surmised, is that Mr. Winchester is a pompous git.
The author's journalistic integrity (having, appropriately enough, a B.S. degree in journalism, I can personally vouchsafe that the phrase "journalistic integrity" is an oxymoron of the first rank) might also be called into question, as evidenced on page 168, where he presents no fewer than three instances of unsubstantiated or undocumented speculation slyly disguised as scholarship, yet allowing enough slippage so as not to hang himself should he be called to task; to wit: "The received wisdom has it...," "It is said that...," and "Dr. Minor supposedly...."
Having half-a-hundred pages remaining to read, I shall make an attempt to refrain from expressing further umbrage should I encounter additional examples of seemingly unnecessary -- that is, seemingly unnecessary to me, at least -- foreign or sesquipedalian (p.75) words where clear, simple, common English language words would suffice.