It seems to me that your problem is not bullies but sadistic adult staff. A child cannot protect himself against such. I don't know English law, but I would be very surprised if this kind of behaviour were allowed. In the US, the hint of a lawsuit is usually enough to get management to do it's job. Several of the people above have given advice that's appropriate if the bullies are other children.....usually. Advice that might work in such situations is useless when the bully is an adult. When members of the school staff are at fault, they must be compelled or removed. I personally prefer removal.