I just heard on QI this evening that to save cloth in the second world war turnups on trousers were banned and boys had to wear shorts until the age of 12. This idea obviously carried on beyond the war as I can remember (like all other boys) having to wear shorts until I went to secondary school. And I was born in 1954! It seemed quite grown up to eventually move on to wearing long trousers. I don’t remember when turnups came back into being though.