There are probably children in his class with worse packed lunches than him.
I'm not defending anyone, but I don't think the teacher can take the blame. She probably did give him some extra food, he was bringing some lunch in, she referred her concerns to the Head (and hopefully the Head referred to Social Care). GP, paediatrician were involved.
Undoubtedly there were things that went wrong and lessons to be learned, but also it is very hard to stop a determined parent killing a child.
It seems there are only two ways to view child protection - it's either social workers destroying innocent families, taking children instead of offering support, misinterpreting things, schools and nurseries blowing things out of proportion and over-referring OR uncaring professionals aren't trying hard enough, ignoring child abuse, appeasing parents.
The emphasis at the moment is keeping families together. Unless the situation is really clear cut - a child discloses sexual abuse or obvious violence to an infant - parents will be offered support and guidance and every effort will be made to keep the child at home. The school had concerns in January or February, this boy was murdered in March - that isn't a huge amount of time for medical investigations, social care investigations, support to be put in place etc.