An exclusive Perth private school received repeated warnings about a sexual predator among its teaching staff over 10 years but failed to remove him from classrooms.

A 60-year-old teacher and former boarding master convicted this week of molesting Year 5 boys was given three written warnings but was allowed to keep teaching primary students until a police investigation began in 2009.

A trail of documents produced in evidence at the man's retrial in the District Court showed that the school's headmasters received detailed complaints from fellow teachers about the man's behaviour towards favoured fair-haired boys in his classes.

His convictions and five-year jail sentence relate to five former students who were groomed and frequently molested by him between 1999 and 2008.

They testified they were "teacher's pets" who would be singled out in the class as his favourites and made to stand at his desk while he fondled them. Some were bullied and teased by classmates. None told their parents until years later.

The teacher's first written warning was in November 1999, when a headmaster told him "a number of your colleagues expressed their concern to me about various instances of contact between you and some of your children to which they have been witness".

In 2001, fellow teachers were so concerned about his behaviour they contributed to a four-page letter to the headmaster outlining an "unhealthy interest in one particular boy in his class each year".

The teacher who wrote the letter said "it appears a pattern (had) emerged" with the physical appearance of the boys who became the teacher's favourites.

She named three boys, who were all complainants in this week's court case.

"Families entrust their children to trained professionals who are believed to have the very best interests of every child at heart and in our case, they pay a lot of money for that as well," she wrote.

"We need to know that the school is not only going to do what is necessary to protect its students and its reputation, but to build a reputation of integrity in all circumstances."

After the letter, the teacher received a warning about school policy but was allowed to stay.

He was warned again in writing in 2004, being told "two of your peers reported that they had seen you with your arm around the shoulder of one child and a boy sitting on your knee".

The teacher and school, who are not named for legal reasons, was told that "should there be further evidence of this kind", the school would pursue his dismissal.

That came in 2009, after one of his former Year 5 students turned 18, decided to tell his family and police about the abuse and a formal investigation was launched.

That former student underwent two rounds of gruelling cross- examination at trials of the teacher, who has maintained he was simply a "tactile person" whose contact with boys was innocent.

In sentencing this week, Judge John Staude said the teacher's victims were innocent children who had been groomed by "praise, encouragement and gifts" and were too young to resist or understand the predatory actions.

"Each boy's vulnerability was exploited by you in a cruel and sustained manner for your own gratification," he told the man.

A former headmaster, who dealt with some of the complaints, testified that at the time he considered the behaviour unprofessional and inappropriate but not criminal.

"I was certainly not under the impression he was a danger to the students," he said.

At the man's initial sentencing in 2010, his lawyer Tom Percy told the court his client wanted to become a priest when released from prison.

That could be as early as June next year.

The school was contacted for comment but did not return calls.

The West Australian

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