An 85-year-old man who was accused of indecently abusing young girls when he was a teacher will no longer have to stand trial.

An Auckland District Court judge has granted wheelchair bound Graeme Collett a stay of proceedings after ruling his medical conditions meant he wouldn't be able to adequately participate in the trial which was due to take place at the end of this month.

"The medical report... makes it abundantly clear that the defendant could not cope with the stress of a two-week trial and it would be life-threatening to him," said Judge Nevin Dawson in a decision released to the Herald.

Collett, who taught at schools on the North Shore before becoming a principal at Mairangi Bay for 13 years, was charged with offending in the 1960s and 1970s against five girls who were aged between 8-10.

News that he will no longer face trial has come as a huge blow to his alleged victims, including a woman who first went to police with her allegations in 1995.

The woman, who can't be identified, told the Herald police were willing to lay charges but warned her it was "her word against his" - a comment that stopped her in her tracks.

"I had a son to bring up and if a jury said not guilty then I (thought) I can't face that therefore I'm not strong enough to take it forward."

Former teacher Graeme Collett was the principal at Mairangi Bay School from 1988 until 2001. Photo / File

Instead, she told police if they could find another person with the same allegations she would take the stand, knowing the case would be stronger and it wouldn't be her word against his. That never happened and she feels it's because they weren't proactive in trying to track down former students.

"I'm disappointed that they have done what they've done now, they could have done that then."

Collett's lawyers referred to the 1995 allegation in submissions for a stay of proceedings - which doesn't reflect a finding of innocence or guilt, just that the trial won't go ahead - saying it was one of several previous chances police had to prosecute.

A second complaint was made against him in 2002 by a person who named two girls she believed had been abused by Collett, but there was no record of the women themselves having made a complaint and no link was made to the 1995 allegations.

Collect came to the attention of the police again in 2005 when the 1995 victim contacted CYFS with concerns about him being seen with a young child. This time connections were made between all of the allegations but the potential victims in the 2005 report could not be located and the file was closed again.

"For the defendant it is submitted that there is no suggestion of bad faith on the part of the police, but they should have investigated the case more thoroughly at the earlier stages," Judge Dawson said in his decision.

"If previous investigations had led to matters going to trial this would have been at a much earlier date when memories would be more reliable and relevant witnesses would have been available."

Former Headmaster of Mairangi Bay Primary School Graeme Collett is helped out of the Auckland District Court in a wheelchair by his supporters.Photo / NZ Herald

He also noted the Crown had acknowledged that "with the benefit of hindsight" police might have been "more thorough in their investigations on the earlier occasions".

Judge Dawson said that while the delays were "regrettable" they weren't a result of "egregious behaviour" by the police.

They were however "detrimental both to the defendant and to the complaints wishing to have their day in court".

Collett's lawyers also argued the former teacher wouldn't receive a fair trial because of the length of time that had passed, the impact that had on the memory of the witnesses and the fact witnesses who could have given evidence on Collett's behalf have since died.

He also has numerous health issues, including advanced Parkinson's Disease, a spinal cord infarct and ischaemic heart disease, that his defence said would impact on the ability to properly participate in the trial.

A report from a neurologist found Collett is cognitively intact and the Crown argued he would be able to meaningfully participate in the trial, albeit with accommodations like shortened days and longer breaks.

However, a report from a cardiologist said Collett's "treatment options are very limited, his prognosis is not good and he clearly has a limited lifespan".

"In Dr Jaffe's opinion the defendant 'is entirely unsuitable to be subjected to stressful situations'." The stress of a court case is likely to render his cardiac condition worse and reduce further his lifespan the judge said in his ruling.

That decision seemed to be the main reason the judge decided Collett wouldn't stand trial.

"I am persuaded that due to the defendant's medical conditions it would not be possible for him to receive a fair trial on these charges."

He said dismissing the charges would act as an acquittal which wouldn't be fair to the complainants.

"I'm therefore ordering a permanent stay of these proceedings in accordance with this court's inherent power to do so."

Collett told the Herald he had no comment to make about the stay.

One of several woman who accused retired educator Graeme Collett of indecent assault says she's devastated a trial won't go ahead due to his ill-health. Photo / Jason Oxenham

Waitematā Detective Inspector John Sutton acknowledged the woman's frustrations at how the case was handled in 1995.

"While it is difficult to find a record of the interactions between the alleged victim and the officers involved back in 1995, there does appear to be areas where police could have made further inquiries."

"This is disappointing for police as our processes around reporting sexual assault have drastically improved over the last 16 years. This is evidenced by the thorough re-investigation into this matter in 2019 after the victim came forward again."

Sutton praised the strength of the women involved in the case and said officers had been in touch with them, particularly the woman who first laid the complaint in 1995 .

"The [women] in this case have shown incredible courage and bravery throughout this process and we acknowledge the decision by the courts is a difficult outcome for them."

The stay comes at a time when many older men are facing charges in relation to historical sexual abuse at Dilworth School. So far 11 men have been charged, three of whom have since died while before the courts.