My daughter has been bullied and my son is being bullied atm. I've never approached the parents, in both cases the child responsible had the kind of parents who didn't know they exsisted and bullies are often victims at home themselves and those children don't really have the kind of parents capable of taking responsibility for their childs behaviour.
The gossip will pass, hold your head up high and don't let this mother bother you. Teach your daughter to do the same with the bully and speak to the head teacher again and again until they take it seriously, keep a diary as nicky suggests but go in after every incident, daily if neccassary and don't give up until they take action.
