When Mexted, the former principal of Westlake Girls High School on the North Shore, was appointed principal of St Cuthbert's in July 2016, a media release said she planned to bring an "innovative approach to education while still being respectful of the college's traditions".
Sources said Mexted, who started work in November 2016, strived to modernise the school's conservative approach to education.
One parent, who did not want to be named, said the school, "conservative to its core", initially embraced the idea of change, but did not like it when it arrived.
On her LinkedIn page, Mexted said in 2017 she led St Cuthbert's through a college-wide strategic and structural review of leadership roles aimed to maximise growth opportunities in a rapidly changing education landscape.
"It was the first review for many years aimed to position the College to continue leading the sector," she said.
Mexted said she was preparing the important groundwork for new initiatives emerging from 2018 to 2020, "while of course respecting College traditions and embracing 'By Love Serve'," the school motto.
Leigh Melville, a trust board member and former head girl of the college, said she enjoyed working with Mexted, saying it was disappointing things did not work out.
Melville strongly refuted the suggestion the school has a conservative approach to education.
"We had a long-serving principal in Lynda Reid (who Mexted replaced) and it's always a big deal when you appoint a new principal when someone was in the role for 20 years," she said.
In response to Herald inquiries, Mexted responded to questions in an email, with coordination from a public relations firm the board uses.
She said she resigned "amicably" following a strategic review and that she agreed with the board that "fresh leadership is required to build on the strong foundation for the future".
"I am leaving very amicably and wish to express my gratitude to the Board and staff. Following the strategic review, I believe that the College is well placed to continue leading the sector.
"The Board has been very supportive of me, and all the hard work I have done for the College over the past year.
"I am hugely appreciative of the support I have had over the past year from the Board, staff, and parents. In my view, the changes that have been made as part of the strategic review ensure the College is in the best possible position to build on the foundations laid. I wish the College all the very best for the future."