There is no way I believe these girls can't get skirts that meet the uniform requirements whether from Skoolkit, or John Lewis / M&S in Southampton
The teachers took these girls shopping - further humiliating them by making them try on clothes in front of them and stand in front of them in their pants (not even sure how this was legal). They tried on 8 (I think) different skirts - the teachers deemed none of them good enough.
So whilst your belief may seem reasonable (after all there was nothing wrong with their original skirts) it is wrong because, according to the teachers, multiple skirts were not good enough. You, me, and the girls and their mothers may have been able to find what looked like suitable skirts - but the teacher deemed them unsuitable for these particular girls' bodies.
The mothers bought skirts specifically from a 'curvy girl's' website (good bye self esteem) but these were inappropriate because they had a small split up the back. They offered to sew the split up. That wouldn't work either.
So then the deputy head went on a nice shopping trip to buy see through skirts ideal for upskirting that would mark them out as different to all the other girls.
Is anybody else creeped out by the idea of the deputy head and his wife going shopping and selecting these skirts, presumably out of school hours? It makes it sound like he is spending his weekend or evenings (and time in his marriage) thinking about these girls and what they should be wearing to hide their perfectly normal bodies 'curves' so that 'boys' aren't distracted.