Idk @DownByTheLakes, you'd hope that they had thought about it very carefully before announcing it, but a few years ago they were confident that they'd strip private schools of their charitable status, and that turned out to be a complete non-starter, so 🤷♀️
I am looking forward to seeing a properly costed proposal, including how many extra state school places will be needed (and not just as a number spread across the country, which makes it look insignificant, because any increased demand will be very lumpy, and some towns/LAs might be completely swamped, whereas others are untouched), how much the net increase in tax take will be after VAT is reclaimed by the schools etc etc.
Sadly, I am not confident that it will materialise. And that's not an anti-Labour comment, I would have no confidence that a Tory govt would produce it either, if this was their policy. They are all as hopeless as each other.
Until someone can prove a net benefit, both fiscal and in terms of educational outcomes and life prospects for all children, then I am yet to be convinced that it isn't just a policy to set one group against another for no real reason other than envy politics.