Sorry thought thread had died.
To answer a couple of points,
MaisyPops
We do understand completely as parents, your point about sanctions. We only really rang for two reasons, he got a detention, usually they email to say so and you agree you know. The school didn't tell us, Ds told us, when asked why he was late home. Second we wanted to be sure it was for eating, it had never been before, so feared he was covering over a worse offence. Also in past the kids got a month to get used to changes, so got strict warnings then it started, unless they did it constantly, suddenly we had new rules and zero tolerance. Also the school failed to communicate any rule changes to parents, and implemented them mid term
If school tell us we will always back them up, would never tell Ds we ask the question. Teacher always right. 
BoneyBack Jefferson
Believe me we had sadist teachers, 2 PE teachers loved the winter, rugby in snow and sub zero temperatures, with only a shirt and shorts. Or Mr Higgins favourite ditch jumping. we had a lovely lad, had a SEN and could not swim because of it, was official excused. But Mr Higgins made him change and come out ever bloody session, then when he refused to jump, actually pushed him into the water, we used to all jump in to rescue him Mr Higgins thought it was hilarious, f8cking t8at more like. Got his come up penance in year 5, when we throw him into the frozen ditch on our last lesson with him.
Also out physic teacher used to patrol classroom with a metal ruler and board compass, if she disapproved of you or someone on your table, you either got the ruler across the back of your hand or on your ear, or the compass stuck in your back or arm.
I had the skin broken more then once. Two teachers left due to complaints of physical attacks, on students. Christ the early eighties where interesting. Maths and Chemistry teachers regularly throw board rubbers at the back wall and even the bloody board compasses.
Though according to my dad, we had it easy if I complained, our teachers, compared to his SM ones, had gone bloody soft.
I think 3/4 of my teachers would have been banned from teaching in todays schools. 
If you hated school, and got nothing from it, why would you tell your kids that school was important.
Please note white WC boys and girls, statistically are the worst two performing groups in education, and people wonder why, sadly it these kids who have parents who school was shit/hard/impossible or you Twagged, ie never went
Actually it's those kids I feel sorry for, they have no chance. I came from FSM WC estate backgrounds, but my parents, as did my wife's, believed education would get us out of it. We totally agree and completely back the school.
Thankfully the MAT, are introducing new codes and have been great at involving both pupils and parents in drawing them up. Surely that's better then expulsions and not telling parents
Sorry I am only a parent.