If parents are genuinely poor then they've got the issue at home as well as school. So again - its not the government or the schools responsibiltiy. Also its cheaper to feed kids healthy food than unhealthy food. Pasties are more expensive than salads and sandwhiches. The problem is that some parents can't be bothered to make their kids a half decent sandwich and teach them about the beneifits of healthy eating - which whould be difficult and a tad hypocritical to do whilst chompoing on a donor kebab, or burying their face into their KFC bargain bucket.
The problem is that some parents are just bad parents and in those cases they need to be assisted by the proper channels - deal with the cause, not the symptom. Palming off these difficult issues onto schools is not the answer - they've got a difficult enough job as it is. And its not only poor families. I've seen it with my own eyes with middle class families where the parents don't seem to make time for their kids and pack them off to school with a bag of crisps for their breakfast and a pasty for their lunch.