The jubilee began on Friday with an afternoon tea for past teachers, followed by a mix and mingle.
On Saturday, there were tours of the school, group photographs, and a ceremonial cake was cut by one of the school's first pupils and one of its current ones.
Sir Jerry was at the jubilee dinner at Wanganui Racecourse. "His speech was great. He was really social and went and sat at different tables." Miss Ashworth said.
On Sunday, a jubilee plaque was unveiled at the school. The names of each year's dux will be added to it.
About 200 people attended the reunion, nine from Australia and one from Cambodia.
"Everyone was very excited to be there and catch up with their old school mates."