Mrs Birling - The Stubborn Upper Class Symbol
Mrs Birling is basically that person who never thinks they're wrong about anything. She rejects all responsibility for Eva Smith's death and refuses to change her views, no matter what evidence the Inspector presents. This stubbornness makes her a perfect symbol of the upper classes who won't admit their faults.
Her marriage to Mr Birling wasn't about love - it was purely a business transaction. She brought social status whilst he provided money, showing how selfish the capitalist system can be. Priestley uses this to demonstrate that even personal relationships become about gain rather than genuine connection.
The way she talks about "girls of that class" reveals everything about her character. That dismissive word "that" creates a massive divide between herself and the working class. She's completely uninterested in the suffering of the poor and sees them as beneath her concern.
Key Point: Mrs Birling acts as a foil to the Inspector - whilst he represents justice and social responsibility, she embodies everything he's fighting against.
Even after learning about Eva's tragic death, she wants everyone to "go to bed and forget this absurd business." Her lack of empathy is shocking - because Eva's death doesn't directly affect her, she genuinely can't understand why anyone should care.