WorkSafe declined to provide a copy of the full investigation report, citing the work required for staff to sift through the 1000 pages.
Following media reports about the absence of Burden and Williams, who have both since resigned, Board of Trustees chairman John Erkkila informed the school community of workplace bullying complaints made to WorkSafe and two independent investigations that had been commissioned by the school to determine what may or may not have happened.
He also acknowledged the slow release of information, citing difficult legal obligations the school had to fulfil.
The summary released by Worksafe said summer holidays meant the case did not progress until the return of school in February when conversations were held with Burden, Erkkila and the board's deputy chair with the first face-to-face meeting being held in early March.
"It was maintained throughout this meeting that there was no truth to the allegations of the complaint," the WorkSafe report said.
WorkSafe concluded that based on inquiries made it was evident there were "systematic failures and gaps in the complaints procedure that prevented workers feeling supported to raise concerns in relation to wellbeing".
The report noted staff, former staff, parents and past Board of Trustees representatives came forward to share examples of bullying they had experienced or seen.
"Although the experiences differed the theme remained consistent that St Peter's School allegedly had a poor culture in relation to staff wellbeing and there was fear amongst staff to speak out about their concerns."
The WorkSafe report said between March and July it received 19 additional notifications in relation to St Peter's however five of those were not directly related to the "current matter" and two decided not to proceed with the process.
In April, WorkSafe staff again met with members of the Board of Trustees to report back on findings and discuss the allegations.
By June the board of Trustees and senior leadership at the school "appeared committed" to making changes, the report said.
The changes included:
• The commissioning of an independent third-party investigation
• New reporting lines with clear procedures for workers on how to raise concerns
• Improved transparency with staff including a new staff representative being
appointed to the board of trustees
• Establishment of counselling services
• Establishment of people and culture committee
• Improved reporting lines to the Board
• Creation of anti-bullying, complaints and whistleblower policies
• Improvements to Health and Safety Representative training and visibility
On June 29, WorkSafe issued the Board of Trustees a formal letter saying they were happy with the improvements under way and "no further enforcement was required".
In a statement, following the end of WorkSafe's six-month involvement at the school, a spokesman said they were satisfied staff well-being would be looked after.
"WorkSafe would like to commend the workers who raised concerns and acknowledge how their actions have led St Peter's School Cambridge to recognise an issue and take positive steps to look after the health and safety of their staff," the statement said.
Worksafe planned to conduct a follow-up assessment in the following months to make sure "the momentum for improvement" had continued.
