The simplicity of it is what strikes me with a jumper or cardigan over a top with tie even if it might of been elasticated for us with short short trousers for us and either a grey skirt or pinafore dress for girls.
What I normally wear is very much the modern version and targeted more toward Infant and Juniors reflecting the changed attitude that saw as we entered the seventies high school boys going straight to long trousers which I did and still loath with a passion