How could edna be the most important character in an inspector calls?

Edna - the parlour maid - represents the invisible working class. Like most girls of her class she has to work, and the most respectable choice for her is to be in domestic service. However, she is regarded by the family as a functionary - in other words she is a maid to clean, fetch and carry: "Giving us the port Edna, that's right." not a person to know. When she is spoken to it is not with the same manners and courtesy that the family extend to each other.

Edna is a symbol of the working class and although she has a small part she is an important member of the household. She shows how women are shown little respect and ostracized by the higher class.