The shocking revelations about Knox have dominated headlines for days and prompted parents of current students to tie ribbons to the school’s wrought iron gates this week as a tribute to the numerous victims.

The 91-year-old Uniting Church school’s many famous alumni include authors, sportsmen, judges, former prime minister Gough Whitlam, and celebrities such as actors Hugh Jackman and Hugo Weaving.

Several former students and parents have given testimony about the school’s apparent blindness to years of abuse.

A 15-year-old student at a nearby girl’s school who attended the Knox campus for rehearsals for a performance of Guys and Dolls in 1989 said Mr Paterson had touched her on the bottom and genitals in view of the male students, who cheered and “chuckled”.

“I saw Paterson had what I would describe as a creepy look of satisfaction on his face,” said Lucy Perry, the student.

A former student said last week of a music teacher named Barrie Stewart: “Often in passing in the hallways he would grab a boy’s genitals. This happened so casually it was like a handshake.”

John Rentoul, a former teacher whose son David attended the school and was molested, wept as he described “the extreme guilt, stress and shame” suffered by his son.

“I believe the school was more interested in protecting the reputation of Knox than ensuring the safety and welfare of its students,” Mr Rentoul said.

During his testimony, Mr Paterson admitted giving glowing references to teachers who were forced to resign over alleged sexual offences and went on to teach at other schools; several were later arrested.

One of these teachers included Christopher Fotis, who is believed to have been behind the “balaclava incident”, in which a balaclava-clad man hid under a dormitory bed and groped a 14-year-old boy. Mr Fotis, who resigned from Knox after he was caught masturbating outside another school, remains at large after a warrant was issued for his arrest last week.

Mr Paterson allowed Fotis to resign for “family reasons” and then gave a glowing reference, describing the alleged sexual abuser as “enthusiastic for his job” and “meticulous in the standards he requires from students”.

Asked why he and his fellow staff members failed to report the balaclava incident to police, he said: “It never entered any one of our heads.” “Controlling the reputation of the school never once entered my head,” Mr Paterson told the commission.

The royal commission, launched three years ago by former prime minister Julia Gillard, has heard tragic accounts of abuse and paedophilia at schools and institutions across the country run by Catholics, Anglicans, the Salvation Army and Jewish groups, as well as at Scouts and sporting organisations.

Mr Paterson began his testimony with an apology and expression of “deep regret” for the years of abuse that occurred during his long term as the school’s fifth headmaster.

“I should have known, and I should have stopped the events that led to the abuse of those boys in my care and their families,” he said.

“My abject failure to secure for you a safe and secure place at Knox strikes at the very heart of a responsibility of a headmaster. This is a source of intense pain for myself and my family.” Mr Paterson is due to give further testimony on Wednesday.