This is a cheap shot to win over voters. It places blame on those who can afford better education, rather than on the politicians who, for years, have totally ruined our state education system.
Where I live, we still have grammar and secondary schools, and a handful of private schools. Going to a private school here doesn't benefit you more than going to a good grammar school in terms of GCSE and A Level marks. It's more for the tradition for the families than anything else.
Really, we need to make secondary schools much more aimed towards learning skills, getting apprenticeships etc so those who aren't as academic can still flourish and get proper gateways into work they'll enjoy. I think grammar schools should remain focused on the academics. Both schools should get more funding that is appropriate to their main focuses. I'd also like to see more of a cross-community relationship between both types of school in the same towns and cities, so allowing students to take classes in the other school if they aren't offered in your own. Also making it easy from students to transfer to one school from another if they realise the other schooling system would benefit them more. It would also help bridge that gap between rivalries between different schools.
I think schooling needs to be tailored to the pupils who will end up attending, and make the most of their skill-set and set them up for life. I do genuinely believe that in England, if grammar schools were brought back, a lot of people would be happier to send their child there than scrimping and saving to send their child to a private one. And if secondary schools genuinely suited kids who are practical rather than trying to keep up with grammar schools, I think a lot more people would end up in stable careers, and doing trades we desperately need.