'why would you then need to send children to private schools through sponsorship?'
because it can't be achieved overnight. In the meantime, the brightest poor children should have exactly the same opportunities as the children of the New Labour MPs who pay for their children to go to private schools out of their publicly funded salaries, which are partially paid by the poor parents of bright kids.
'Surely the answer isn't just to make exams harder, without improving standards of teaching, expectation, making classes smaller and working with parents to try and get them to support their children and have aspiration for them. I also think that if private schools offer better teaching and more subject choices then state schooling either needs to keep pace or we need to find another way of levelling the ground.'
I agree, it's not only about making exams harder, it's about curriculum change etc. and better teacher training and if money permits, then smaller class sizes etc. But I don't believe in preventing the rich from having the freedom to spend their money as they please. I don't believe in levelling down, I believe in levelling up.
Just as most rich people will choose NHS care for serious conditions, because the publicly funded NHS is often better than any private hospital, then so too could they choose publicly funded schools rather than private ones, because there is no reason why a publicly funded school could not outperform a private one. But it will take time to improve the standard of all schools.
'Some parents don't support their children and some times it can be as simple as the parents and school not sharing the same values.'
That is true, but that can be equally true of rich parents too. I don't believe in the 'nanny state' blaming parents for their children's lack of success. I think it is the state's fault, the state that pretends it cares, that pretends it is a "nanny", but does not improve the standard of the schools that the children attend. It's not the fault of parents that we have poor literacy levels in schools, it is the fault of the schools and the state.
Imagine if when public education was first introduced, when parents were illiterate, that the 'nanny state' blamed the parents. The state was responsible for education, not the poor parents.