There she was, writing two speeches: the one she had to share with authorities before the big day – and the one she really planned to give.

Haynes, the outgoing school captain of elite private girls' school Ravenswood, on Sydney's upper north shore, told the speech day audience she felt "let down" by the school she loved.

I really hope her parents were at her side, giving her all the support she needed; as she planned to take down the image of the perfect private school.

Private schools have access to just one tool in the armoury for student recruitment that public schools don't have. Private schools get to spend hundreds and thousands of dollars on selling a lie. Public schools must depend on the wit and wisdom of their state and territory governments to broadcast the great, great goodness of our public system.

Public education advocate and author of What Makes A Good School, Jane Caro, agrees: "Private schools are selling a brand and an image but what goes on in the classroom, goes on in classrooms in every school all over Australia.

"There is nothing unique about what goes on in private schools, unless you mean unique in terms of luxury, but that's about it."

The other aspect of private education – and maybe this is what some parents actually want – is the ability to select students based on something other than merit or proximity to home. The myschool website shows you just how different Ravenswood is. While the Index of Community Socio-Educational Advantage (ICSEA) divides Australia into four quartiles, the Ravenswood student body has just 2 per cent of those who would fit into the bottom half; and 84 per cent in the very top quartile. Perhaps it's hard to keep those big earners if they think they aren't buying perfection.

Ravenswood is now in damage control (if you can call the pathetic response by the chairman of the school council Mark Webb where he says he can't recall how the audience responded to Haynes' speech, an attempt at damage control) but in reality, the educators should be pleased. Here is a young woman speaking up and speaking out. There should be so much more of it.

Haynes revealed that earlier this year she had planned to give a speech at an open day where she would be honest with prospective parents about the bad and good aspects of the school but was told to change the ending.

"I sent [the planned speech] to those in charge of me and received a reply: 'Great speech but change the ending. No parent wants to hear that the school isn't perfect'," she said.

It was, Haynes said in her speech, a school too driven by image, too driven by financial considerations; and, by extension, where more value is "placed on those who provide good publicity or financial benefits", she said.

A school driven by image – that's the expression that should ring alarm bells with every parent. She said that every time she was to speak on the school's behalf, she would be censored. "I was never trusted to say the right thing."

There is, of course, always a back story to events like these. Sometime during the year, Sarah Haynes' sister left Ravenswood. The circumstances are not clear – but leaving mid year indicates that something wasn't quite right. Maybe her sister never really fitted in with the expectations of what it meant to be a "Ravo" girl; maybe she got into more trouble than her school captain sister who confessed that even she had experienced the odd spot of bother. I know year 8 girls can be difficult, believe me, but how bad can it be?

"I am far from the model student. I have been kicked out of geography class, I've had a detention and I've said things that have hurt people . . . the person who doesn't make mistakes is unlikely to make anything," revealed Haynes.

But clearly Haynes wants much more from the school. She wants them to learn, just as the school expects its students to learn. She has said she did not give the speech because she wanted revenge for her sister but because she wanted the school to do what it expects of its student.

"We learn from mistakes," she said. "The only dangerous thing about mistakes – which I think Ravo may have lost sight of this year – is not being able to recognise and admit to them."

Here's what parents all over Australia, including those who spend thousands of dollars at Ravenswood, should hope for all their children.

One, a decent and generous response by the school to concerns from families. In the case of Ravenswood, surely the principal – at least – could acknowledge her bravery. It's not the same bravery as going to school from a refuge or as a refugee with a handful of English words, but taking on any establishment is brave.

Demand a school board and a school council which is accountable to the real stakeholders, the students and their parents. And Ravenswood, get the resignation of that far-too-cautious chair. Mark Webb is an embarrassment.

Demand transparent school processes and make a fuss if you don't get them.

And Sarah Haynes, go into politics. We need a few more women willing to speak up. And you are one.

Twitter @jennaprice or email jennapricejournalist@gmail.com