Some children do seem to have 'bully me' written all over them. That doesn't excuse the bullies behaviour in any way but I do think that we have bought up a nation of wimps because mothers (mostly) do too much for their children instead of training them to be more independent. On the other hand, the bully's parents have probably let them have their own way too much with little discipline in the early years.
I tell my young granddaughter, at the first sign of any bullying, to stand up and look them straight in the eye and say very loudly something along the lines of, 'I do not want to be friends/socialise with you etc. because you have a horrible personality and those who hang about with you only do so because they are scared of you and you must have a very sad life to behave in this manner. If it (the incident) happens again, I will take it directly to the Head Teacher'. This can be adapted to whatever the situation is but the idea is to nip the bullying in the bud.
Hopefully, he or she will be so dumbfounded by this tirade that there will enough time for the 'victim' to walk away safely. If a bully is tackled at the first opportunity they, hopefully, will back down because they are often cowards themselves and won't want to bother anyone who has a strong personality. The sad thing is they will probably move on to someone else.
Parent also need to deal with their own children in an appropriate manner if they are found to be the actual bullies and there should be legal or social consequences if they do not.
I read some of the comments on mumsnet and I despair at the mums who think their kids can do no wrong and that the school rules don't apply to them. You have the - 'My child won't drink water, why can't the school allow juice?' brigade or 'why can't my child go to school with braids in their hair' etc. In an ideal world there would be no bullies and no victims but a child's personality is formed in the home in the early years so make sure you are not helping to produce a victim or a bully.