It occurred one month after Fox spoke at a public meeting in Newcastle as part of the Newcastle Herald's Shine the Light campaign for a royal commission into institutional child sexual abuse, and one month before his dramatic allegations on the ABC's Lateline program that led to a royal commission.

Kaldas delivered the apology at Newcastle police station, after reviewing police handling of a case that started in June 2006 when another Hunter police officer sprayed pepper spray in the face of a young man in the back of a police van.

I'm writing about it today after extraordinary evidence to a NSW parliamentary inquiry from some of the state's most senior police officers, including Kaldas and Commissioner Andrew Scipione, about police handling of allegations involving other police, and the NSW Ombudsman's handling of those allegations.

The Hunter pepper spray incident also led to police allegations against other police, subsequent investigations, and a review by the NSW Ombudsman's office. It ended with Kaldas's apology to Fox, and Kaldas's opinion that adverse findings against two other senior Hunter police officers were "also bad".

In both cases the subjects of allegations argued strongly - if internally - for years about the need to be advised of what exactly it was they were alleged to have done wrong, so that they could respond.

Kaldas's review of a complaint lodged by Fox in December 2011 shows how extraordinarily matters can stray if that basic requirement of any investigation is not understood, and followed.

Procedural fairness matters, in other words.

Two Hunter police investigated a complaint by two other police after the 2006 pepper spray incident. They found the officer who sprayed the young man had no case to answer. This was ratified by other Hunter police.

The NSW Ombudsman thought otherwise.

Fox was asked to review the police investigation and findings. This was his first involvement with the matter.

Over the following weeks Fox raised serious questions about both the investigation and findings. Those concerns were shared by other senior Hunter police who reviewed his review.

An internal complaints procedure panel directed Fox to seek legal advice about charging the officer who sprayed the pepper spray, and investigate the "inadequate" internal investigation of that officer.

By February 2008, after receiving Fox's negative report about the internal investigation and his view that the officer who sprayed the pepper spray should be charged, Fox was authorised to lay the charge.

A few weeks later yet another senior Hunter police officer conducted yet another review - this time of Fox's investigation and findings. By September 2008, and without being interviewed, Fox and two other senior Hunter police officers who had simply ratified Fox's findings found themselves with formal adverse findings against them.

During the same period the officer who sprayed the pepper spray was convicted and fined $300.

The officers who found he had no case to answer had adverse findings against them withdrawn.

Quite bizarrely, the adverse review against Fox alleged he was part of a "boys' club" that appeared to be operating within senior ranks of Hunter police, despite indications it was Fox's recommendations that might have upset the "boys' club".

More investigations followed. Kaldas's review and findings show a number of senior Hunter police had roles along the way, but the formal negative findings stayed in place until July 2012 when Kaldas overturned them.

It is interesting, now, to read that report, particularly after my own experiences with the NSW Police Force at the NSW Special Commission of Inquiry, and the extraordinary animosity shown to Fox by certain elements in the Police Force that continues to this day.

The pepper spray saga is just one of two festering internal police matters I'm aware of involving Fox and other senior Hunter police in the period before that inquiry. Any airing of those matters was excluded from the inquiry with the consent of the NSW Police Force. But there is no doubt that simply having contact with Fox ensured my "guilt by association" - of what, exactly, was never clearly defined.

In the end Commissioner Cunneen found "no evidence" that I had done any of the things the police implied and insinuated throughout the inquiry, which I think entitles me to say I was subject to baseless allegations.

An apology? And pigs might fly.