I felt compelled to share my experiences also... I went to a grammar school and started in 1987 (20 years ago - oh my goodness!). I had previously been in the top 2-3 in my class and 'big things' were expected of me, according to my head and teacher in primary.
I enjoyed the first year, then I became angry and tired of the elitist attitude, I was cross with the pressure without support, and 'opted out' (or physically walked out sometimes). I stood my ground and locked horns with some important teachers. I exerted more energy on avoiding lessons and key teachers than I did working. I left there with mainly B's, but some C's and D's and went straight into manual work, so glad to leave the stifling atmosphere.
I spent 4 years standing still but when I had my son I realised I wanted more for him, and for me. So I am now qualified in the profession I eventually chose (at the age of 21), and earning my original full-time wage many times over each year. I take education very seriously now, but didn't for a long time and felt like a real drop-out when my friends stayed on for 6th form, went to uni, and I was working. I feel the school really knocked my confidence by not allowing me to progress at my own level and not encouraging me to enjoy my own personal achievements. I am so glad I went back to evening classes, but it may not have happened.
I very much hope that some of what I experienced is now well out of date. The attitude from my teachers was the same my mother had experienced 20 years prior at the same school, so perhaps I am being too optimistic that times would have changed for my son!