@parker231 I do believe that a reasonable dress code is sensible. Allowing kids to wear anything would just give one more reason for kids to be bullied and for social differences to be highlighted. Yes, all of that can still happen, but why provide more reasons for bullying etc?
But the dress code must be reasonable.
It must be weather appropriate, nay, lighter and heavier options should be permitted and it should be up to the kids to decide. Waiting for the head to decree when it's hot enough is sick.
At work I may go out to lunch wearing just a short polo while my colleagues wear long shirts and a midlayer on top - none of that is unprofessional, heat tolerance is subjective.
Items should be generic, available from anywhere, not from a specific supplier only, and headteachers shouldn't obsess about the exact shade of grey or the exact number of millimetres - to me that is always a sign of repressed, unhinged characters having a power trip and getting off with this display of authority. Let's not forget that every job which involves a degree of authority over other people can attract unhinged individuals - that's why the police should have checks and balances for that (which don't always work, sadly).
In my mind it would be something like: dark grey trousers, shorts or skirts, with long sleeved shirt or short-sleeved white shirts or polos (I'd get rid of the tie but know many disagree), and an optional navy jumper (no blazer). During the winter, dark-coloured coats with additional layers to be worn as needed (I trust we can all agree that the teachers in this case were mentally unstable https://www.chroniclelive.co.uk/news/north-east-news/jesmond-park-academys-uniform-policy-26016890 )
Tights shouldn't be compulsory, at least not between May and October; the same for leather shoes: wearing leather shoes with thick socks in July can be torture.