None of your points make any sense.
the existence of private sector education directly and negatively affects the quality of state education
How exactly?
if private education was banned, there’d be a lot more wealthy people with spare cash which could be taxed and put into state education
Huh? We don't tax wealth on this country, we tax income. The government has already taxed every penny of income the parents use to pay for private school. They will typically have taken a minimum of £15k out of an earned £35k (leaving 20k for school fees). They may have taken up to £33k out of an earned £53k tax (leaving £20k for school fees). Let that sink in. They may have already taken more income tax than the education itself costs.
the more entitled people advocating for state education, the better it will be
Hahahahah.. Who do you think we'll be advocating with?
Labour do the exact opposite of listening to us. Teachers are overwhelmed: do you think they'll try harder if we tell them to???
No. The more children there are in state schools with existing resources (or less, if more than 10-15% of children move) the worse it will be.
But it is directly subsidy, because I am pretty certain that there will be almost no decline in private school places.
That makes the least sense of all. You can't just put the word 'because' in when the 2 things are unrelated.
There is no subsidy. The government is giving £0. We are saving the government £7k per child per year. That's why each child who moves from private to state increases the state cost.