I have found the actual Appeal Court judgement on the Denbigh School case:
Update: URL moved
It bears out, so far as I can see, my interpretation in my previous post:
75. The decision-making structure should therefore go along the following lines:
1)Has the claimant established that she has a relevant Convention right which qualifies for protection under Article 9(1)?
2)Subject to any justification that is established under Article 9(2), has that Convention right been violated?
3)Was the interference with her Convention right prescribed by law in the Convention sense of that expression?
4)Did the interference have a legitimate arm?
5)What are the considerations that need to be balanced against each other when determining whether the interference was necessary in a democratic society for the purpose of achieving that aim?
6)Was the interference justified under Article 9(2)?
81. Nothing in this judgment should be taken as meaning that it would be impossible for the School to justify its stance if it were to reconsider its uniform policy in the light of this judgment and were to determine not to alter it in any significant respect. Matters which it (and other schools facing a similar question) would no doubt need to consider include these:
Whether the members of any further religious groups (other than very strict Muslims) might wish to be free to manifest their religion or beliefs by wearing clothing not currently permitted by the school’s uniform policy, and the effect that a larger variety of different clothes being worn by students for religious reasons would have on the School’s policy of inclusiveness;
Whether it is appropriate to override the beliefs of very strict Muslims given that liberal Muslims have been permitted the dress code of their choice and the School’s uniform policy is not entirely secular;
Whether it is appropriate to take into account any, and if so which, of the concerns expressed by the School’s three witnesses as good reasons for depriving a student like the claimant of her right to manifest her beliefs by the clothing she wears at school, and the weight which should be accorded to each of these concerns;
Whether there is any way in which the School can do more to reconcile its wish to retain something resembling its current uniform policy with the beliefs of those like
the claimant who consider that it exposes more of their bodies than they are permitted by their beliefs to show.
In other words, the school didn’t write the correct arse-covering memos before deciding to apply its school uniform policy.