Two quotes
."The Battle of Waterloo was won on the playing fields of Eton."
"I could not love thee, dear, so much, loved I not honour more." (That one's from the Civil War.)
The Waterloo one annoys me because of the attitude that anything important's done by the tiny minority of people whose families can afford to send them to schools like Eton, but school stories do tend to be about that socio-economic group, and the point is that the "rules" in school stories tend to be about playing fair, being sporting, being a good sport, being part of a team, not doing anything that's not cricket, and various other things involving sporting terminology
. EBD isn't obsessed with sport itself in the way that Enid Blyton is, but the idea is still generally to play fair and put the good of the school/team ahead of your own wishes, and to be truthful and honourable. Girls are expected to stick to school rules even when they could get away without doing so, e.g. speaking the language of the day even when there are no teachers or prefects around to tell them off if they don't. Anyone who's done anything wrong is expected to own up, lying and betraying trust (Grizel doing a runner when she's supposed to be in isolation) are severely frowned on, and sneaking is one of the worst sins of the lot. On the other hand, it isn't good to be too good: anybody who's "frightfully pi" or, worse, a teacher's pet, will be unpopular. Nice naughtiness is good!
Leadership's also a big issue, and again this is possibly because of the idea that the people in school stories are from the ruling classes. It probably comes across best in St Clare's, where they have the fagging system. & in most school stories, being emotional or being a wimp (Gwendoline Mary and the swimming pool!) are frowned on, and being brave and battling through the pain barrier are seen as positive things, but that doesn't happen so much at the CS where people are always bursting into tears and everyone's obsessed with putting health first. Sometimes that seems to extend to the strong picking on the weak, which to me doesn't fit in with fair play at all but does seem to happen a lot.
There was a move against soppiness at one point, which comes across most strongly in the Dimsie books. In earlier school stories, such as Angela Brazil's, there seem to be a lot of Grand Passions and so on, but it's frowned on in later books, and people like Alison O'Sullivan and any of the soppy girls in the Dimsie books are laughed at and seen as being silly.
Actual schoolwork never seems to be a very big issue
.Some books do show "sneaky foreigners", like Claudine and Antoinette in the St Clare's books: they aren't unlikeable, but they don't quite understand about playing the game. Like the sneaky foreigners at FIFA who awarded the 2018 World Cup to Russia when the English bid was so much better, or the sneaky foreign strikers who dive for penalties and try to get opponents sent off when of course English players would never do such things (it's quite worrying how some sections of the media genuinely do seem to believe this
). Sorry, I've written an essay there. Very bored at work!
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) Elizabeth Gilbert memoir - the main character and some Italian and Swedish friends are sitting about talking about how each city has a single word that represents it, like 'New York' is summed up by 'achieve' - and all nationalities agreed that London's word was 'stuffy'. Which seemed to me to suggest the writer had never in fact been to London, or not to my bit, or to Soho after chucking-out time, or to the City during the Christmas party season, anyway. 
), or has a huge passion for something (Nina Rutherford & music, Eustacia & reading/solitude) that's seen as a problem - they have to learn not to be too "one-sided".
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