Here's why:
* The political and social context: The novel mentions the rise of fascism in Europe, with the narrator feeling the impact of these events. The 1930s saw the rise of Nazi Germany and Mussolini's Italy, leading to the build-up to World War II.
* Fashion and Technology: The book mentions cars and radio, technologies that were becoming more common in the 1930s.
* The narrator's age: The narrator is young and inexperienced, suggesting she was born sometime in the 1910s.
* The references to the First World War: The characters are all young enough to have been impacted by the First World War, which ended in 1918.
Therefore, the most plausible setting for *Rebecca* is the 1930s, likely sometime between 1934 and 1938.