How the St Peter's Cambridge bomb scare unfolded

St Peters School in Cambridge was the subject of a bomb threat last month. Photo / NZPA

The former principal of a prestigious private school, who resigned during an investigation into allegations of bullying, told police he could not help when they told him of a bomb threat.

Police arrived at the on-campus residence of the former executive principal of St Peter's School in Cambridge, Dale Burden, just before 8pm on May 13 to inform him of a bomb threat at the school.

Burden, who had not been seen at school since before the end of the school term, told the sergeant he was "not currently in a decision-making capacity", according to police records.

He instead referred police to chief operating officer Rob Campbell.

The threat came the same day the school's board chairman John Erkkila informed parents bullying complaints had been made to Worksafe in term 1 and the school had hired independent investigators to look into the situation.

The previous day WorkSafe had confirmed it was making inquiries about "staff wellbeing" at the school amid the absence of Burden, and his wife and deputy principal Yevette Williams.

The school confirmed Burden and Williams no longer lived on campus. The Herald understands they moved out during the weekend.

Dale Burden resigned as executive principal of St Peter's School in Cambridge during a bullying investigation. Photo / Sarah Ivey

According to police records, shortly after 8pm on the day of the bomb threat Sergeant John Reid spoke to Campbell in his office at the school where he advised him of the threat which was reported to Crimestoppers anonymously.

Campbell then called other members of the school executive to work out a response.

He also organised extra private security for the school for the night and police agreed to carry out extra patrols of the school grounds when able.

Police advised that the school be extra alert to any suspicious items and, should any be found, evacuate and call 111.

St Peter's Trust Board chairman John Erkkila said there was discussion with police about the validity of the threat and the confusing nature of the wording used.

"In consultation with police and the school's emergency management specialists, Harrison Tew, the school decided any risk was unacceptable, hence the decision was made to evacuate," Erkkila said.

The final night of the school production, Chitty Chitty Bang Bang, was underway when Campbell was told of the bomb threat.

"Students involved in the production and those in the audience were informed at the end of the performance by campus principal Julie Small that a threat had been made and they would all need to leave calmly and not return to school the following day," Erkkila said.

The next communication between the school and police was at 10.48pm when police were told all boarding school students were being moved to the Velodrome next to the school. Parents were informed of the threat and cancellation of school the next day by email and social media, a school leader, whose name was redacted, said.

Parents received an email just after 10.30pm informing them of the bomb threat and evacuation. Parents were told they could collect their children throughout the night.

One concerned parent told the Herald an email was not enough and the first they heard of it was a text from their daughter.

Erkkila said he was proud of the way the school community managed to relocate 500 students and staff off-campus in a quick and orderly fashion.

He also praised those who offered to billet students until they could move back onto the campus, and those who provided food.

Police later told the school they would continue patrols overnight and have a specialist search squad on the grounds in the morning. The school noted their concern about when classes could resume and when students could go back to retrieve medication left behind when they evacuated.

Waikato West area commander Inspector Will Loughrin later said police had completed a thorough investigation and found there was no credibility to the threat.

"We are aware this was a distressing situation for the school, its students and parents," he said at the time.

"We want to reassure the community, we take matters of this nature extremely seriously and any new information that comes to our attention regarding this incident will be assessed accordingly.

"Police will be providing ongoing support where necessary to the school and its community."