On Thursday, Bishop Peter Carrell told the Abuse in Care Royal Commission he thought the number was about 30.
RNZ reported on Friday a survivor of abuse at the school, Jim Goodwin, had been told the figure was much higher.
The extent of historical abuse at Christ's College in Christchurch is still unknown.
Bishop Carrell went to the school himself, and while he had a happy time there, he is aware this was not the case for everyone.
''There would be a variety of reasons why that would be a difficult time. Some of that we do know is through abuse, that is completely unsatisfactory.''
He said as many as 80 people could have suffered abuse, given the number of boys who have passed through the school over the years.
''This is communication of unsatisfactory school experience which may or may not also involve a specific complaint about abuse.''
Jim Goodwin boarded at the school and was sexually abused by three senior students in the early 1970s.
In 2020 he told the inquiry about the abuse and that his housemaster had found out.
''So, I wouldn't tell him anything so I sat in his office trying not to cry and try not to bleed on his chair because I was bleeding. He called that whole year together, I wouldn't tell him who they were. He called them all together and told them he would expel them if they touched me, and they never did again, they said a few things but they never touched me again.''
Jim Goodwin's abuse did not trigger any formal investigation by the school or diocese.
The Bishop sits on the board of Christ's College and is Warden, a type of pastoral overseer.
Bishop Carrell admits better oversight of schools is needed, particularly in his diocese where he is warden to a number of Anglican schools.
''How much more proactive I could be in the life of each school if you like without the school wondering why their warden had suddenly become rather proactive.''
Archbishop Philip Richardson also took to the witness box and unreservedly apologised on behalf of the church to survivors of abuse.
He called it unacceptable and inexcusable.
''An apology, although sincere, may be seen as incomplete without tangible redress processes and structural changes that prevent such shameful conduct occurring ever again.''
''The Anglican Church has made substantial changes in the way it responds to incidences of abuse to insure that its institutions are safe for everyone especially those children, young persons and vulnerable adults that we care for and provide services to.''
Archbishop Richardson called on anyone abused within the church who has not come forward to do so to the Royal Commission.
The latest figures on cases of abuse within the Anglican Church nationwide are 132 from within its churches, 168 from its care organisations and 248 from Anglican schools. A total of 548.
