Ms Isherwood said while she had later realised the letter was ageist, her criticism was solely based on the skirts and did not extend to the school as assumed by several follow-up letters that were published.
"I wasn't judging the book, I was judging the cover ... I have no doubt it is a good school."
Woodford House principal Julie Peterson said while the school wants their students to feel proud wearing the uniform, they also want them to know that the clothes they wear don't "define" who they are as a school.
"Woodford House is a leading school for girls - not because of our uniform, but because of our exceptional teachers, our academic results, our stunning facilities and our strong history," she said.
Ms Peterson also said the uniform, which was last changed in the late 90s, was in the process of being reviewed as it was "time for a fresh approach".
The school began to consult with the school's community in August 2016 and expects the new design will be introduced next year.
The Woodford House uniform was backed by several follow-up letters written to Hawke's Bay Today.
Havelock North resident Jenny Greig said upon viewing the photograph her first thoughts were of a confident and mature group of students.
"The letter was pointed and rude, but demeaned the author far more than the target of her opinions, an innocent group of young women, and a school focused on the quality of learning."
Takapau resident Judith Lyons said some parents are glad to be part of a school that "promotes modesty" and also mentioned the uniform review.
"The Woodford House community does not need help to change "ancient attitudes" but it does need help with people passing judgement without having a full understanding of the situation at large."