"everyone thinks they're an expert on schools" I have not said once I was an expert on anything. I said this one punishment was unfair and OTT.
Teacher should absolutely be supported. I have supported the teachers at my dd's old school a lot. The assumption seems to be if you don't agree with everything you must agree with nothing, that is not true.
But our first job as parents is to be there for our kids, not to stop them ever being punished, but to make sure that they are receiving fair treatment, IMHO.
"Parents are my biggest stress without any doubt - bigger than OFSTED, paperwork, workload. The shit that parents have put me through in the past 15 years is untrue." THIS is very sad and very wrong, but I would hope (as you sound very nice and kind) that you would be sensitive to body issues for teenage girls and not single them out for potential ridicule in this way because you were upset by a comment.
"We do them no favours fighting their battles for them." If school seek to disempower them, we may need to empower them. I think we are discussing two different issues from two totally different sides. i have seen the harm school does to some, you have seen the harm done to some by others. I don't want to waste your time arguing with you. I honestly respect good teachers and I don't wnat to stress you out, you won't convince me of the error of my ways. All the best. 
FrancisCrawford "Actually italian it was more a case that he was chosen to do this. he was resresenting his country at international level, you see." So utterly unrelated to punishment at all. But good on him all the same, hope he won. 
Now I mus go because I can't be bother to argue the toss and the washing up needs doing, and if i do not do it maybe DH will make me run round the garden in my underwear!
Night all 
OP PM me if you wish to, all the best.