Sheila Neiler is a first-form student at St. Clare's whose father recently acquired significant wealth. This new-money background fuels her insecurity among peers from more established families. Her struggle to fit in manifests as putting on "airs and graces," behavior that causes many in the form to dislike her.

A notable incident occurs when Sheila uses the non-standard grammatical phrase "You didn't ought to..." during a conversation. Janet Robins publicly rebukes her, stating sharply, "Haven't you learnt by now that decent people don't say 'Didn't ought to'!...you talk like the daughter of the dustman!" This humiliation underscores Sheila's social vulnerability. Later, head girl Winifred James explains to the O'Sullivan twins that Sheila's insecurity stems directly from her family's new status and perceived lack of social refinement.

Excluded from participating in the first form's French play after Mam'zelle selects Joan for a role, Sheila is instead assigned the role of prompter. This responsibility fosters a sense of inclusion and contributes to a partial easing of the earlier tensions with her peers.