i'm not sure that AF dismisses the feelings of Pomona or Marie, so much as that she conceals them, at least from the characters. I think it is a really interesting depiction of the way a group can treat an outlier, and not realise they are doing anything wrong. I do think it's clear to an adult reader, and I think I got that when I first read it at about the same age as the characters. Even here, though, I feel sorrier for Pomona (quite a lot, really) than for Marie, who is not a likeable character. (The one thing I find implausible is that she had been able to 'boss the Second' the previous year.)

Generally, I think the characters are brilliantly drawn from the start.

One thing that strikes me on this read is that there is no mention of rationing, which was still in force for lots of things when AF wrote it. A deliberate attempt not to date the book?