Every time it’s hot during school time, you hear of schools still insisting that their pupils wear blazers or just their jumpers. https://www.hulldailymail.co.uk/news/hull-east-yorkshire-news/kingswood-academy-send-home-defiant-121507.amp
https://www.oxfordmail.co.uk/news/19462070.wearing-school-blazers-heatwave---readers-say/
What do schools think they are going to achieve from not relaxing the rules? Nothing. More pupils becoming ill, parents keeping their DC away.
It’s barbaric behaviour. Yet I doubt that they make the teachers, non teachers staff wear blazers and wear summer clothes with short sleeves.