The headmaster of an elite school in Sydney’s CBD has written a letter to parents urging them to “chill”, warning them aggressive behaviour won’t be tolerated.

St Andrew’s Cathedral School Principal Dr John Collier wrote the open letter to parents (see the full letter here) after dealing with “too many parents who have verbally abused, physically threatened or shouted at a staff member”.

He tells Deborah Knight parents need to be “called out”.

“I want to be clear at my own school, it’s only a tiny minority of parents who behave this way.

“But if any parent should behave that way, I think it’s unacceptable and it’s unhelpful. It doesn’t actually assist in resolving the problem, it just raises the temperature and makes the resolution more difficult.”

Dr Collier says “modelling” from certain people in the spotlight is “unhelpful”.

“Some politicians, some sportspeople… demonstrate this level of verbal aggression and unfortunately they are prominent in the public eye and other people copy this.”

Click PLAY below to hear the full interview