Pamapuria School Commissioner Larry Forbes, who was appointed this month, said the revelations that Parker was involved in this abuse came as an "enormous" shock to the school and caught everyone by complete surprise.
"It was just a sense of disbelief that this could possibly be the case, so it was stunning news for people and they've had to deal with it in their own way since that was disclosed."
Today's guilty pleas and the lifting of name suppression meant it opened up the chance for the school to move on.
It would conduct its own thorough investigation, but Mr Forbes said they were being careful not to compromise the police investigation.
Detective Senior Sergeant Kevin Burke said there was a dedicated 0800 number - 0800 900 502 - so any member of the public with information could assist.
Parker - who was a highly respected and liked member of the community - had not been back to the school since the charges were laid because he was taken into custody following his arrest.
The school's Board of Trustees resigned when they realised what was ahead of them, Mr Forbes said.
He was in charge of starting an investigation to find out how abuse could happen over an extended period of time.
"I'm sure there will be a lot of questions asked within the investigation and a lot more that will come out of it that we will need to answer, the scope will be huge."
It was general believed that the offending did not happen on school grounds, but the investigation "might throw up other information".
The school had already worked quickly to review practises in the school to ensure it was a safe place, Mr Forbes said.
Counsel Alex Witten-Hannah told Radio New Zealand (RNZ) today that in 2009 police wrote a strongly-worded letter, alerting the school to a tentative complaint about Parker's behaviour.
He said the letter warned that Parker should not be allowed to have children stay at his home.
However, the school did not act on the warning, he said, and pupils continued to go home with Parker.
Mr Witten-Hannah said most of Parker's offending happened after the police warning.
The former chairman of Pamapuria Primary School's board of trustees, Ian Bamber, told RNZ that he knew nothing about the warning but plenty of people did.
He said he learnt of the letter this year, and has since discovered many others already knew about it.
"ERO knew about the letter, police knew about the letter. CYFS knew about the letter, and the board at the time knew about the letter."
Mr Bamber said it appears the one person who was not warned by police was Parker.
Teachers' Council director Peter Lind said the council was made aware of the case when it went before the courts.
Because he was unlikely to be out of jail in the next few months and will not pose a direct threat to children - the Council would wait for the full police investigation to be completed before they decided whether Parker would keep his registration.
This was a distressing case of somebody in high trust abusing that trust, Mr Lind said.
"... By far the great, great majority of New Zealand teachers act professionally and appropriately, however, any case that involved the sexual abuse of a child or young person is a serious matter and has consequences for those young people that is significant. We need to get those people out of the classroom."
Thirty teachers have been struck off since 2010, nine because of sexual abuse of a child or young person, he said.
The guilty pleas come a day after the release of a ministerial inquiry into the failings that allowed convicted sex offender Henry te Rito Miki to teach in six North Island schools using 53 fake names.
It said the Education Ministry had insufficient evidence to confirm Miki was a risk to children.
The release came as it emerged the Teachers' Council does not know how many sex offenders are working in New Zealand schools.
A 2006 Education Review Office report into decile three Pamapuria School said it was well regarded in the community and enjoyed high levels of support from its Maori community.
It said all staff knew the children well.
PARKER'S STATEMENT IN COURT
Parker was permitted to read a statement in court in which he said his thoughts were with the young people he had abused and their families.
"Words cannot express the total shame, guilt, regret and sorrow that consumes me day and night because of the things I have done.
"Believe it or not, these crimes were committed against people I care about very much. I wish I could fix the damage I have caused.
"My crimes have also had awful and drastic consequences for my school community, students, staff, parents, board of trustees and principal.
"You are all indirectly victims of what I have done. As a teacher and deputy principal I held a position of great trust. My actions betrayed that trust. I have let you all down, causing huge amounts of unnecessary stress. I am truly sorry.
"To my family and friends to whom I have caused immense hurt and unthinkable distress, I cannot even bring myself to beg your forgiveness...
"Those of you who know me well will know that I am not the monster that many will portray me to be. I am, however, the unwilling host of a most terrible disorder.
"It is my great hope that all who have suffered because of me will now be able to get the help they need. It is also my desperate wish that I too will be able to receive help for this sickness within me."
Parker said he would grieve over his actions and the suffering he had caused for the rest of his life.
"All I can say is I'm sorry."
