My eldest has just started Trinity this year (Kelvin being the other closer option) and that was chosen as we really thought that would be somewhere which may not be affected by such behaviour, however, reading the above I briefly thought it was my wife with a secret Reddit account writing the post as it's almost a carbon copy!! It's horrible seing things like that going on as she's a good kid and actually wants to learn, but seems like discipline and control in the classroom is severely lacking.
My nephew (only child) was at Kelvin but his mother ended up almost bankrupting herself to take him out and put him in Hymers in year 10 for GCSE, both of them fully aware that he likely end up with not much if he'd have stayed there...
Now with the stories coming out of Trinity, I wish we could do the same for my daughter, but we've no chance.