Priestley portrays Sheila as, at first, a victim of her mother’s influence.
However, after the Inspector's arrival, there is a distinct shift in their relationship; Sheila rejects her mother’s manipulation.
Initially, Sheila is obviously influenced by her mother’s formal vocabulary, evidenced by Sheila’s
use of the adjective "impertinent" when she describes Eva, linguistically echoed by her mother
later.
However, Sheila, towards the end of the play, rejects the use of this adjective, calling it “such a silly word”. It is clear that from this point onwards, Mrs Birling has lost all influence and power over her daughter