The local BBC news article stated that the school had said that the pupils could "loosen their tie a little" as a way to solve the issue. Yes, showing about 1cm of skin on your neck will supposedly solve the problem of being stuck in stuffy classrooms with no airflow, 30+ degrees temperatures. high humidity, sun pouring in through the windows and being stuck in black trousers all day long - in a country that is not used to temperatures over 20. Generally shows how the headteachers are so obsessed with terrible rules that they place it over the health of the students.
UK school dress code is just a general trainwreck, in primary school shorts and trainers are perfectly fine, move up to middle school and suddenly they are prohibited, jump up to high school the rules get so strict that you get in trouble even if it's for health related and you have a note from the headteacher - except certain pupils openly flout the rules without any pushback because double standards. Meanwhile the teachers wear whatever they like.