Thanks for the clarification, Paw. I figured it was something like that. The USA version of the punishment was writing sentences on the blackboard after school. In rare instances, if the teacher determined public humiliation was necessary, you'd have to do it in front of the class. That wasn't a particularly efficient use of class time, however. This sort of punishment still existed when I was in grade school (the late 1950s) but it was more often seen in cartoons and TV shows than in real life.
Similarly "corporal" punishment. I always disliked that term. It sounds like you're beating a foot soldier. Anyway, during my grade school years spanking (usually with a paddle custom-made by its user) was still permitted, but it was rare and considered the domain of a few loose-cannon teachers. By the time I left high school in the late 60s most states had outlawed the practice.
I realize it's dangerous to draw conclusions from comics, but school story papers give me the impression that beatings were an integral part of the English education system.
I missed the "lines" up 'til now because I haven't read many of the boys' school stories. I never warmed to them. The boys are combative and behave like jerks to one another (like real boys), and too many stories concern sports, a subject that never interested me.
To tell the truth, between the real world and contemporary media I have become so surfeited with violence that it's comforting to dip into the fantasy world of the girls' comics, where the stakes are much lower and everyone (except the Mean Head Girl, of course) treat each other with a modicum of respect. It's rather pathetic, really. I haven't yet sunk to the level of embracing "Pet Club" stories, so maybe there's still some backbone left in me.