A very public war between the old and new guard at Melbourne's prestigious Trinity Grammar School has reached new heights.

On Wednesday, a truck mounted with LED screens with messages calling for the headmaster and school council to resign circled the school at pick-up time, upsetting students, parents and teachers.

It's the latest salvo in a deepening rift over the direction of the school, which was exposed when deputy headmaster Rohan Brown was sacked by the school council for cutting a student's hair on school photo day.

Sorry, this video has expired Trinity Grammar Deputy Headmaster trims student's hair on photo day

The sacking triggered mass protests by students calling for "Browny" to be reinstated, a vote of no confidence in headmaster Dr Michael Davies and school council, and a statement from the 2017 school captains calling for Dr Davies to resign.

The two sides are digging in, with the powerful old boys' association threatening legal action and an independent review into Mr Brown's sacking underway.

'If you want academic excellence there are other schools'

David Baumgartner believes Dr Davies has changed the school's culture. ( ABC News )

Old Trinity Grammarians' Association president David Baumgartner said Dr Davies is changing the culture of the school.

"This is not about Rohan Brown," he told 7.30.

"This is about the change in the school's culture and he is the line in the sand, the lightning rod that has brought it all to the fore."

Mr Baumgartner has led the charge against what he sees as the headmaster's increased focus on academic results at the expense of producing well-rounded young men.

"Trinity has a unique position, culturally, in the Melbourne environment," he said.

"If you want excellence academically, then there are other schools you can choose to send your child to.

"If you want the best person you can choose to turn out, then you send them to Trinity Grammar."

In November last year, Mr Baumgartner wrote to the school council criticising the new direction of the school and the treatment of staff under Dr Davies.

And he urged others to do the same.

"We ended up with about 140 pages of four- and five-page emails talking about their concerns about the direction of the school."

Mr Baumgartner said the headmaster's position is now untenable.

"I don't know how Dr Davies can remain as headmaster of the school," he said.

'It's not about the haircut'

That view is echoed by last year's five school captains.

Earlier this week they published a 2,000-word statement laying out their criticism of Dr Davies and calling for him to go.

Denis Curnow says the protests are about the school's future, not about the haircut. ( ABC News )

Denis Curnow, a 2017 Vice-Captain, said when the captains raised objections to Dr Davies about his style of leadership they were dismissed.

"Whenever anyone raised criticism about the way he was going about his actions we were not heeded, we were not listened to," he told 7.30.

"Eventually it got to the stage where we no longer had any faith, any trust or any confidence, in the ability of the current administration to run the school.

"It's not about a haircut, and anybody who has any slight connection to Trinity knows it."

Supporter of headmaster calls for protests to stop

Shan Morrison thinks the protests against Dr Davies have gone too far. ( ABC News )

But Dr Davies has supporters among the current parents.

Shan Morrison is the mother of two current Trinity Grammar students.

"For the four years that Michael Davies has been there we've seen the school just go from strength to strength," she told 7.30.

"Overall I just think the vision and the direction of the school is fantastic."

She can't believe what is happening with the protests.

"A group of parents and old boys, who I don't think are representative of those groups, are carrying out a campaign which has been really conducted in a way that is not demonstrating the Trinity values," she said.

"It has gone too far and I think it needs to stop."

'Dr Davies will not be resigning'

Trinity Grammar is backing headmaster, Dr Michael Davies. ( Source: Trinity Grammar, Melbourne )

In statement to 7.30, Trinity Grammar said the school had been inundated with private and public messages of support over the past week.

"Dr Davies is leading a school direction that builds on Trinity's established vision and values, while increasing opportunities available to young men in the context of a global environment. He wants every boy to thrive and be the best possible version of themselves," the statement said.

"In past decades — be it as a teacher or headmaster — Dr Davies has always acted in the best interests of students. Sometimes, this might require a strong voice, which is part and parcel of the role of being a school leader."

The school stressed that Dr Davies had not been part of the code of conduct hearing or the decision to sack Mr Brown, which, it said, was led by the previous school council chairman.

"Trinity Grammar is unequivocal in its position that the school should uphold, every day, the highest standards of staff and student behaviour," the statement said.

"Dr Davies will not be resigning."

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