Who is Mrs. Potter from Love Takes Wing and what is their importance?

Mrs. Potter appears to be the head of Mrs. Stafford-Smyth's household servants. Mrs. Potter gives Belinda a disapproving look when she tries to help gather the tea things after tea is served. She is also openly resentful when it is announced that Belinda will be served as one of the guests at Mrs. Stafford-Smyth's dinner party.