I think Joan's 15 in this book. That doesn't seem young to be interested in boys, and Janice Chester, at a similar age, mentions in
Adrienne that some of her friends at home have boyfriends - but there does seem to be a very snobbish attitude in this particular book that only "common" girls show an interest in boys before they're of marriageable age.
Margot's problem with Ros is definitely rewriting history!
I think it's awkward for both of them. It's never easy to be the new kid at school, when everyone else has known each other for years - although it does happen quite a lot at the CS. It must be even more difficult when you are from a different background to the others. Everyone just expects Ros and Joan to know what is and isn't done - and the same thing happens to Thekla, Eustacia, and various others who aren't from the usual CS background. The dormitory scene in which someone keeps talking to Joan in French even though she's explained that she doesn't speak a word of French is ridiculous.
Jack does pressurise Mary-Lou into taking Joan on, but why did Mary-Lou have to be talking to Jack about her in the first place? What business was it of hers if Joan talked about boys? I find her a real busybody in this book. But I think the whole thing is that everyone is expected to conform. A lot of people, especially at school, will submit to peer pressure and do whatever in takes to fit in, and that's at all schools, whether they're day or boarding and whatever the socio-economic background of the pupils is. That's what Ros does, and I don't blame her for that. I'd've done the same, because I like a quiet life! But I do quite admire Joan for being more true to herself.
The thing I really don't recognise from my schooldays is how conformist the other girls are. In my day

, yes, there was a certain amount of pressure to dress a certain way (when out of uniform), and be into certain things, but that was all about what was considered the done thing by your peers, not to obey school rules. Did none of the other CS girls ever "customise" their uniforms, or try to get away with wearing make-up when they weren't allowed to, or use the odd swear word? Had no-one else ever called Matey names behind her back? Was it really only Joan who didn't just do what she was supposed to?!