The now-70-year-old man denied all accusations to police after a victim came forward to her father eight years after one incident occurred.

Eventually, he pleaded guilty for two acts of indecency towards one child aged between seven and 10, and for inciting a seven-year-old to an act of indecency with himself, between 2008 and 2011 in the Riverina region.

The man who was married to the grandmother of the two children between 1999 and 2019, took her grandson fishing in 2008.

As the young boy lay down on a steep bank the man touched his genitals but was disturbed by another vehicle driving through the reserve, causing him to cut his penis on the zipper of his pants while putting it away.

After the vehicle drove away he again touched himself while the boy noticed blood from the injury.

Another time the boy was sitting on the front passenger's seat of the man's vehicle while he was driving when he unzipped his pants and repeated his offending for up to five minutes.

Then sometime around 2011 the young boy's sister sat on the man's lap before jumping to see his genitals completely exposed.

"Do you want to touch it?" the man said, to which she replied "No".

In 2019 she disclosed this incident to her father and the man was arrested.

The man was opportunistic in waiting to be alone with each child and abused his position of trust, NSW District Court Judge Gordon Lerve said in his judgment on Wednesday.

A clinical psychologist's report found the offender "is now left a lonely isolated man, who has few if any friendships," and stays in bed most days sleeping after drinking at least half a litre of wine a night.

He "categorically repeatedly denied attraction to young children," and continues to deny the offending and was deemed without insight or remorse by the court.

It was noted that he attended a Christian Brothers School where "a lot of physical abuse occurred", but denied any sexual abuse.

"I find this whole process very distressing. I am unable to properly articulate how I feel, except to say that I feel sickened that the children have been hurt," the man wrote in a letter to the court.

He was sentenced to a total term in prison of two years, and will be first eligible for parole in July 2022.

The age of the offender and his ill-state of physical health afforded him "a very generous finding of special circumstances," on sentence, Judge Lerve said.

Australian Associated Press