Conversation so far:
What are the stereotypes involved in this article?
Christie occasionally inserted stereotyped descriptions of characters into her work, particularly before the end of the Second World War.
What kind of stereotyped characters?
(when such attitudes were more commonly expressed publicly), and particularly in regard to Italians, Jews, non-Europeans, and sometimes Americans, the last usually as impossibly naive or uninformed.
Are there any other interesting aspects about this article?
In The Hollow, published as late as 1946, one of the more unsympathetic characters is "a Whitechapel Jewess.

Question: Why is it an unsympathetic character?
Self-contained rewrite: Why is  "a Whitechapel Jewess" an unsympathetic character?