The findings follow 13 former students telling public hearings in late 2015 that they were sexually abused by staff between 1956 and 1989, and describing a culture of cover-ups and negligence at the prestigious private school.

The royal commission found that John Lewis, who was principal from 1980-1994, allowed convicted paedophile Jonathan Harvey unsupervised access to students despite knowing that the former maths teacher was accused of abuse, including trying to have sex with a student. 

Former Geelong Grammar teacher Jonathan Harvey. Photo: Luis Ascui

"With that knowledge, Mr Lewis permitted Harvey to occupy a position where he had unsupervised access to students," the Commission found.

"Mr Lewis did not take any steps to prepare policies or procedures to protect the safety and welfare of the students at Geelong Grammar."

Mr Lewis went on to become headmaster of Eton College, where he taught Prince William.

Nicholas Sampson, now principal of Cranbrook School in Sydney, leaves the Royal Commission into Institutional Responses to Child Sexual Abuse. Photo: Jason South

Nicholas Sampson, who who was principal at Geelong in 2004 and is now the headmaster of prestigious Sydney school Cranbrook, received allegations about Harvey that dated back to the 1970s, but allowed Harvey to remain at the school on full pay for the remainder of that year.

He did not report Harvey to police or the teaching regulator, the Victorian Institute of Teaching, or make a record of the reasons for Harvey's departure at the end of the school year.

The royal commission said Mr Sampson should have kept better records, but accepted that he was trying to act in the victim's best interests and would now behave differently if faced with a similar situation.

It was also found that Geelong Grammar allowed a former teacher, BIM, to work at the school in the late 1990s, despite knowing the teacher was or may have been jailed for paedophilia.

The school "preferred its financial interests" to the victim's best interests, in failing to tell a victim about the abuser's employment history at the school, while the victim was seeking compensation, according to the royal commission.

In the late 1980s, a former headmaster at the school's Highton campus, John Robert Bugg, forced a student known as BIW to leave the school, after the boy told other students that he had been sexually abused. Mr Bugg told the student to keep the matter secret, the royal commission found.

"In removing BIW from the school and not investigating the complaint, Mr Bugg failed to protect BIW's interests and the interests of other students at Highton", the royal commission report said.

John Buckley was a teacher and housemaster at Geelong Grammar's Glamorgan primary school campus in Toorak. Photo: Michael Clayton-Jones

Five former Geelong Grammar School staff members – Graham Leslie Dennis, John Hamilton Buckley, Stefan Van Vuuren, Philippe Trutmann and Jonathan Harvey – have been convicted of child sex offences.

The royal commission found that while the school has since introduced formal systems, policies and procedures to deal with child abuse (which they did not have before 1994) there is no system in place to ensure teachers are reporting allegations properly.

The school also keeps what is called the 'K files', which contain confidential information about staff or students which are stored separately to the general files to limit access.

The school's principal Stephen Meek sent parents a letter on Tuesday, thanking survivors for coming forward during the royal commission hearings and apologising for the school's failures.

"We are also very sorry that some of the school's former senior staff neglected to respond to some of our past students with the respect and protection they so rightfully deserved," he said.

"The School deeply regrets the wrongful conduct by some of its former staff and I assure you that the current school leadership will continue to address these matters and support those affected."