My favourite school, with the least bullying, was actually a school with a "bad reputation" in a "poor area". Public school too. When rumour spread about fights or bullying happening, the older kids would go and watch out for the younger ones, and break anything up. The teachers were a bit useless, so we dealt with it ourselves. A disabled boy came halfway through the year and was picked on because he was an easy target - until half the year 11s/12s decided to "adopt" him as a sort of little brother. We even took turns walking him home to make sure nothing happened to him as he had fits and we didn't want him to be hurt.
Just so I'm clear here, we never turned to bullying the bullies, so to speak. We just found that if they were very clearly called out on their behaviour, they lost their bravado and left quick smart.