The Birlings' maid, Edna, may seem insignificant but she serves as a reminder of the Birlings' wealth and the presence of the lower classes. She also introduces the Inspector and provides insight into the life of Eva Smith since they come from a similar background.
Edna is portrayed as being loyal to her employers despite their mistreatment of her. This highlights the power dynamic between the upper class and working-class individuals during this time period.
Her name, Edna, could be interpreted as symbolic of the oppression faced by women at the time. It could also represent the idea of 'everywoman', highlighting how the issues raised in the play are relevant to all people regardless of gender or social class.
She is described as having "a kindly face" which suggests that she has a good nature and is trustworthy. However, she is also referred to as "the girl who cleans up" which emphasizes her low social status.
She is described as having "a face that was not pretty" (Act One) which could be interpreted as a commentary on how society values physical appearance over character or personality.
As the main protagonist, Edna undergoes a significant change in attitude, behavior, and overall character throughout the course of the novel, as she becomes aware of and examines the private, unvoiced thoughts that constitute her true self.