Peter Creigh was a key witness in the landmark trial of Wilson, who on Tuesday was found guilty in Newcastle Local Court.

Magistrate Robert Stone said Wilson failed to report to police the repeated abuse of two altar boys by pedophile priest James Fletcher in the NSW Hunter region in the 1970s.

The 67-year-old, who showed no emotion, is the most senior Catholic official in the world to be charged with concealing child sexual abuse.

He faces a maximum two years' jail.

Mr Creigh, close to tears after the verdict, said it was a "huge relief" and labelled it a "significant day for victims and their families".

He believes everyone in the Catholic Church hierarchy should be made accountable if they had known victims were being abused but remained silent.

Prosecutor Gareth Harrison told the court Wilson should be jailed to deter others from trying to protect the Catholic Church from abuse allegations.

Another victim of Fletcher's, Peter Gogarty, agrees, saying the decision set a "massive precedent".

"I think this will now open the doors for other jurisdictions to start looking at trying to prosecute people who deliberately looked after their institution and literally threw children to the wolves," Mr Gogarty told reporters outside court.

Daniel Feenan, whom Fletcher also preyed on, said if Wilson had gone to the police in 1976 - the year he was born - the priest ''would never have got to me'' and his life would have been very different.

''I'm just glad I could sit in court and eyeball him (Wilson). He knows what he's done,'' Mr Feenan said.

Mr Stone accepted Mr Creigh and another altar boy told Wilson in 1976 that Fletcher had repeatedly abused them but the clergyman did nothing.

Mr Creigh trusted Wilson, then an assistant priest, would take action after being told of the abuse when he was 10 in 1971.

Wilson had worked with Fletcher and lived with him for a short period but denied they were friends.

Mr Creigh had not told his parents about the abuse when he made the "momentous and defining decision" to confide in Wilson, Mr Stone said.

"He (Mr Creigh) was a genuine and truthful witness who did his best to accurately recount what he had told the accused," the magistrate told the court.

"Further, he had no motive or self interest in any way to deceive or to make up the conversation (with Wilson in 1976)."

The magistrate rejected claims by Wilson, who is suffering from the early stages of Alzheimer's disease, that he could not remember the altar boys telling him of the abuse in 1976.

He suggested Wilson had a sense that he knew "what he was hearing was a credible allegation".

"In addition, the accused wanted to protect the church and its image."

Fletcher was found guilty in December 2004 of nine counts of child sexual abuse. He died in jail of a stroke in January 2006.

In a statement released by the Catholic Church, Wilson said he was "disappointed" by the guilty verdict.

"I will now have to consider the reasons and consult closely with my lawyers to determine the next steps," he said.

The defence had argued Wilson was not guilty because the case was circumstantial and there was no evidence to prove the archbishop was told about the abuse, believed it was true or remembered being told about it.

Sentencing is due to start on June 19.

Australian Associated Press