Cracks Begin to Show
As the Inspector's investigation progresses, the generational divide between Sheila and Mrs Birling becomes impossible to hide. Mrs Birling desperately tries to protect her family's reputation by treating Sheila like a child, telling her to "go to bed and forget about this absurd business."
The real conflict erupts when Mrs Birling dismissively refers to Eva Smith's social class, saying she doesn't understand why "girls of that class" commit suicide. Sheila immediately warns her mother to stop "for your own sake," showing her perceptive nature and growing social awareness.
When Mrs Birling calls the Inspector "impertinent," Sheila responds by "hysterically laughing." This moment marks the turning point where Sheila realises her mother's arrogance and begins to ridicule her outdated attitudes. She's essentially becoming the Inspector's voice within the family.
Key Point: Sheila transforms from obedient daughter to moral guide, while Mrs Birling remains stuck in her privileged bubble - their relationship completely reverses.
By Act Three, when the family discovers the Inspector was fake, Sheila maintains that "it doesn't make a difference" whilst Mrs Birling calls her "childish." Ironically, Sheila has become the mature one, representing hope for social responsibility and change that Priestley believed the younger generation could achieve.