A school in Sydney paid tribute to a teacher alleged to be a "notorious molester" with an inscription on its memorial gates that read "he touched us all", Australia's royal commission has heard.

Former Knox Grammar School student Scott Ashton told the inquiry he was deeply confused by the memorial at the school, the response of which to the abuse allegations is the subject of the investigation.

Ashton said that Bruce Barrett, who died young, was a "notorious molester" but prior to his conviction of five counts of indecent assault and two counts of sexual assault in 2009 students were expected to pay tribute to him.

"The fact that he was so well regarded by the school despite being a notorious molester made me feel very confused and powerless," he said.

(Picture: Google)

"I felt ashamed of my abuse. I was deeply ashamed and unable to discuss it with anyone.

"It was an issue which I avoided because any reminder of it would cause me severe stress and interfered with my ability to function and cope on a day-to-day basis."

Mr Ashton alleged that Barrett would chase and tickles his pupils, and used to announce "watch out boys, it's a read tie day" meaning he would be caning people.

The 44-year-old said that he was asked to stay behind after class by Barrett one day, but instead of being caned was sexually assaulted.