Yes, there's a tiny margin of acceptability at EB schools. You can't either try too hard at lessons (Ellen Thingie the scholarship girl), or not enough (Gwen). You have to be mischievous to the correct extent, or you're 'pi' and goodygoody ('St' Catherine), but not too much and your pranks have to be the Ordinary Jolly Schoolgirl kind (Alicia's tricks, Bill sneaking out to see her horse), not breaking bounds to sing in a 'common' talent content (Mavis). Good at sports (Darrell, Felicity), but not obsessive (Amanda). You have to be generous, but not too generous (Jo Jones 'buying' her classmates' liking with feasts). You're not allowed to be 'sensitive' or homesick (Gwen, Maureen), but you're also not allowed to be too 'hard' like Alicia and June. You have to be humble or you're forcibly humbled (poor Sheila, the O'Sullivan twins), but not too humble (St Catherine again). You have to have the 'right' kind of fault it's OK to be Darrell with a temper that makes her repeatedly assault people, but not to send anonymous letters or pretend to be ill to get out of games or exams.
You can have a governing talent that makes you eccentric, but only if the other girls recognise and 'allow' it to be genuine (Irene and Belinda -- but if Irene was composing gloomy post-Schoenberg atonal stuff, rather than catchy dance music for the school panto, or Belinda was a monochrome cubist rather than a caricaturist, would they have been allowed to get away with so much?)
And what if unpopular, show-offy Maureen turned out to have written excellent songs, or good costume designs, for the pantomime, would the others have admitted it, or even recognised they were any good?
Actually, I think Belinda's caricatures and the fact that she stalks dislikeable characters to draw their scowls, as well as her continual depictions of the well-meaning but irritating Catherine as a saint in a stained-glass window, which she puts up publicly, are some of the cruellest forms of bullying in the series.
And you are not allowed to breathe a hint of criticism of your parents ever, unless of course you have the Wrong Type of Parents like Gwen or Jo Jones or the Honourable Angela, in which case you are supposed to recognise this and not follow their example at all.
Dizzying!