Archbishop Wilson's evidence in 2013 that he had forgotten communications with anti-corruption crusader MP John Hatton in 1987 about "sexual misbehaviour" complaints involving McAlinden and young children was "improbable", Commissioner Margaret Cunneen found after an inquiry into police and Catholic Church responses to Hunter child sexual abuse allegations.

The future archbishop assured Mr Hatton in a letter in July, 1987 that his complaint about McAlinden was "receiving attention". Their communications also included phone contact on four occasions and a further letter in which the then Maitland-Newcastle Vicar General assured the MP that McAlinden had left the parish for "a full program of psychiatric assessment and help".

The confidential fourth volume of the Special Commission of Inquiry was released more than five years after the first three volumes were made public, and following Archbishop Wilson's conviction in 2018 for concealing child sex allegations about Hunter priest Jim Fletcher, which was overturned on appeal in December.

The Commission regarded as "unsatisfactory and implausible" the archbishop's evidence in 2013 that he had "honestly forgotten" liaising with a psychiatrist about McAlinden, and talking with the priest by phone on five occasions between October, 1987 and February, 1988.

Mr Hatton's report was one of a number of complaints about McAlinden to the future archbishop in 1987, the Commission found.

While the Hatton letter was raised during the inquiry hearings in 2013, Archbishop Wilson's role - including having a direct confrontation with McAlinden, referring him to a psychiatrist and repeated phone calls with the paedophile priest before he was moved to Western Australia - has not been revealed until now.

The complaints about McAlinden addressed by the then Father Wilson in 1987 included a statement taken by him from a Merriwa mother who alleged McAlinden sexually abused her daughter. The abuse was "of a serious nature, demonstrating McAlinden's interference with children", the Commission found.

Father Wilson advised Mr Hatton on July 20, 1987 that his concerns about a complaint against McAlinden in 1976, and several "apparently new" complaints relating to Merriwa, "were receiving attention from diocesan authorities".

The Hatton complaint, sent to Sydney Archbishop Clancy and referred to Maitland-Newcastle diocese, provided "impetus" for the diocese to act, the Commission found.

The Commission of Inquiry found Father Wilson was already aware of a complaint about McAlinden by the time of the Hatton complaint, after a close friend told the future archbishop in 1986 or 1987 that she had been sexually abused by McAlinden as a child.

Father Wilson believed the woman's account and relayed it to then Bishop Leo Clark but took no further steps, including "exploring with (the woman) her attitude toward reporting to the police", Commissioner Margaret Cunneen found.

"Wilson's failure to consider on any level the question of reporting the matter to police meant that an opportunity for a police investigation into McAlinden at that time was lost," the Commission found.

Only two weeks after Father Wilson's response to Mr Hatton he received a phone call from Merriwa Catholic school principal Mike Stanwell who reported "another case" involving McAlinden.

Father Wilson noted in his diary Mr Stanwell's view that "people were willing to take action", and on August 4 he spoke with McAlinden and Mr Stanwell by phone.

The Commission found Bishop Leo Clarke and Father Wilson confronted McAlinden at Adamstown about the allegations. Clarke suspended McAlinden, but by late 1988 the priest was working in Bunbury, Western Australia, where he was later accused of sexually abusing at least one young girl.

It found the then Maitland-Newcastle Vicar General Wilson read a psychiatrist's report noting the first allegations against McAlinden were in 1954.

The archbishop told the Commission his responsibility "ended with reporting the matter to the bishop".

"He held this view despite his awareness of the continuing danger McAlinden presented to children," the Commission found.

A note in his diary in 1987, setting out the main elements of the common law offence of misprision of felony - concealing a serious crime - "contradicts Wilson's evidence that he did not turn his mind to the question of potential criminal liability" relating to his knowledge of McAlinden's offending.

"What Wilson knew at that time... would unquestionably have been of interest to police" and should have been reported, the Commission found. It rejected his evidence he was unaware McAlinden had been sent to Western Australia.

The Commission found Father Wilson, who by 1995 had a degree in canon law, initiated a formal diocese attempt in that year to stop McAlinden working as a priest, in a canon law process "on the basis of psychiatric disabilities".

Father Wilson took statements from two sisters sexually abused by McAlinden as children, and told the Commission it "did not occur to him that McAlinden should be reported to police".

"By this time Wilson was acutely aware of McAlinden's offending, extending over decades" and that he was "still at large and potentially had unsupervised access to children", the Commission found.

"His failure to report McAlinden to the police cannot be justified and amounted to a failure to facilitate and/or assist a police investigation of McAlinden."

The notorious paedophile priest, who arrived in the Hunter from Ireland in 1949 at the age of 26, and committed child sex offences against an unknown number of very young girls for decades, was charged with child sex offences in Western Australia in 1992 but acquitted. He died in a Western Australia Catholic Church aged care facility in 2005 without facing further charges.

A 1995 document written by Bishop Leo Clarke urged McAlinden to agree to moves to remove him from the priesthood, and promised that his "good name will be protected by the confidential nature of this process".

Maitland-Newcastle diocese has paid compensation to a woman in New Zealand who was sexually abused as a child by McAlinden when he was sent there in the early 1980s. McAlinden also spent considerable periods in Papua New Guinea, England, Ireland and the Philippines.

Archbishop Philip Wilson was contacted for comment.