Noted on page 117, Beatrice mentions "Harrods" when talking to our unnamed Narrator (N) about clothing or shopping after her and Maxim's marriage. Beatrice is shocked to hear that N hasn't gone into London and used her new found money to dress herself into the new status she is in. This a more minor mention but is very telling of Beatrice point of view and how N fits into her new role as Mistress of Manderley.
When looking up the context of Harrod, I learned that Harrod isn't just a luxury department store in London, but it is thee luxury store. Harrod has grown since 1849 as a grocery store to a global tourist and lavish shopping plaza. Harrods houses 300 departments, 20 restaurants, a bank, grocery and high end designer clothing and jewelry, making it the largest department store in all of Europe. This is a world known store and sought after by tourist and upper class society for years.
In context of Rebecca, Beatrice mentions Harrods as a commonly known store to N for clothing. Beatrice says it so casually because she assumes N is keen on the social norms of high class living, but is surprised. N being new to this is quiet and just lets Beatrice blabber on and on. But this interaction shows two things, Beatrice idea of upper class and how N should be and also N's understanding what expectations are had for her. Beatrice is used to fancy stores, lavish clothing and upper class life that a mistress of N's position should be living, an example is how Rebecca lived her life. Rebecca embodies that upper class woman persona that N lacks as a newly mistress and being raised in a more modest lifestyle. It shows to the audience that their is expectations and N is, again, not living up to those newly found expectations; continuing to broaden the gap between Rebecca and N.