The Royal Commission into Institutional Responses to Child Sexual Abuse was told that the family owed $25,000 in tuition for their son.

The teenage student, given the pseudonym CLC, was allegedly indecently assaulted by a fellow student while on a cadet camp with the school in April 2013, the inquiry heard.

When The King's School's bursar raised the unpaid fees with headmaster Tim Hawkes in September 2013, the commission heard CLC's father was described as a "bad debtor".

The inquiry was told Dr Hawkes wrote to the bursar advising: "Failure to pay his debts should result in the usual sanctions including the boy being sent home and him being put in the hands of a collection agent."

Dr Hawkes told the commission he had a meeting with CLC's parents in October 2013 which was secretly recorded by CLC's father, given the pseudonym EAE.

In handwritten notes made before the meeting and tendered the commission, Dr Hawkes writes that CLC should have followed the school's anti-bullying policy and disclosed the alleged assault and subsequent bullying earlier.

"It was this failure to make an immediate disclosure that contributed to CLC's alleged harassment," he wrote.

Dr Hawkes told the commission he did not blame CLC for the alleged bullying he endured.

The inquiry heard the school's anti-bullying policies failed in relation to CLC, who left the school in October 2013.

CLC's father compared his son's experience to a "single chicken being pecked to death" in his evidence to the commission.

Evidence before the inquiry into child-to-child sexual abuse in both public and private schools is that The King's School has dealt with a number of such allegations.

The North Parramatta school has dealt with four historical allegations of child-to-child sexual abuse and some contemporary claims during Dr Hawkes' 19 years as headmaster, he wrote in his statement to the commission.

The inquiry continues before Justice Peter McClellan​.

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