I was privately educated, i never went to a state school of any kind.
I think my mum sent me because she believed i would get a better education. At Primary school, there were only 10 of us in my class, so we definately got more attention from our teacher, but I'm dyslexic, and my dyslexia went unrecognised and untreated, in the end, i had to repeat a year because i was never offered any extra help.
when i was 10, my mum sent me to boarding school, which i hated, and never forgave her for. It was like an expensive prison for kids who hadn't done anything wrong. She sent me there to get specialist help for my dyslexia, as the school boasted about its reputation for hiring expert tutors to help with dyslexic pupils, but to be honest i still struggled, and my teachers often overlooked me, even in the subjects i was really good at, because of my shortcomings in other areas. As you might expect, there was a lot of rivalry and one-upmanship and "my daddy drives a Porche, well, my daddy drives a Bentley" etc etc In the end, i got less GCSE's than all my friends who went to the local comprehensive, who by this time i had largely drifted apart from due to being away for so long.
I lost my dad when i was a baby, and my mum never re-married, throughout my school life i was one of the only kids who didn't have a dad, which left me vulnerable to teasing, whereas i think if i'd gone to a state school it wouldn't have mattered. I hated my school so much i refused to stay on for A-levels and got into a dead-end office job.
I'm not saying my experiences are typical of the public school system, but i would never ever send a child of mine away. Personally, i think my mum wasted her time and money, and i think she came to realise that by the end. Most of my friends who went to state schools got a better education.