Gender Roles and Patriarchy
Women in 1912 were expected to be pretty, quiet, and completely dependent on male relatives for everything from money to major decisions. Sheila starts the play fitting this traditional feminine role perfectly - she's engaged, obsessed with clothes, and defers to her father.
But watch how Sheila's character develops throughout the evening. She becomes increasingly independent, challenges the men's authority, and ultimately sees the truth more clearly than any of the male characters. This transformation reflects Priestley's support for gender equality.
The contrast is deliberate - Priestley wants his 1945 audience (who'd just seen women work in factories, join the forces, and prove their capabilities during the war) to reject the restrictive gender roles that trapped women like Sheila.
Character analysis: Sheila's growth from obedient daughter to independent thinker mirrors how British women's roles changed between 1912 and 1945.