In my school it was the other way round. Until 11 years old it was shorts all year but then we werent in any sense fashion conscious at that age so it didnt matter. Blazers ( different edging for prefects and rugby / cricket squad) up to lower 6th and then sports jackets if you wished.
One odd one was a guy of celtic / welsh heritage who had very dark hair. Grew a full beard at 16 and in an era when beards were rare anyway. Looked odd in assembly but the school didnt object.
Dont see how skirts for boys can be a problem when Scots wear them frequently.
