"So you learn a lot from that sort of business experience and commercial experience as well."
One of the greatest things about the state secondary school, which has 2450 boys and 150 teachers, was the immense sense of pride and loyalty it generated, Mr Morris said.
"Those boys are definitely Grammar boys for life and that's been very special to be a part of that and I feel very privileged to have been headmaster."
Mr Morris, whose own son went through the school, has seen huge changes in the way pupils are taught.
In 2001, he introduced the University of Cambridge international exams to New Zealand.
"No other school was doing it. International qualifications were unheard of in New Zealand at that stage, so bringing it in was something very special, he said.
"I did it because I thought we needed it for our boys, but it's grown to more than 60 schools that are offering the qualification now."
He also saw change from the School Certificate qualification to the NCEA system - something which he says was flawed from the start.
In January, Mr Morris dumped NCEA level 1 for Year 11 boys in favour of the Cambridge exams, which he said better suited the learning style and nature of most boys.
"We made that decision purely for the boys ... We wanted something that would keep the boys motivated."
The difference in the boys' reports and their attitudes to learning had changed dramatically this year because of the decision to use Cambridge exams.
"The boys are turning up to their exams, they're staying for the whole three hours, whereas before it wasn't like that under NCEA."
The school still offers NCEA as a backup.
Mr Morris says that if he managed to maintain Grammar's standard, ethos and traditions while making the school more humanitarian, that is what he would like to consider as his legacy.
Mr Morris will leave the school next September.
"I guess from my point of view it's a good innings - almost 20 years at the school - and I've always wanted to leave still energetic, still passionate and still loving the job ...
"It just felt the right time tomove on and do something a little bit different."
The school's old boys include Sir Edmund Hillary, Oscar-winning actor Russell Crowe and his cricketing cousins Jeff and Martin Crowe. It has also produced 50 All Blacks, the most from a single New Zealand school.
