William disappeared from his foster grandmother's house in the NSW town of Kendall about 10.15am on September 12, with police and neighbours alerted by 11am.

The NSW Coroners Court on Thursday was told Paul Savage, who lived across the road, had given a number of statements to police about his movements that day.

But no statement included a conversation the 75-year-old now says he had with the foster grandmother shortly after a neighbour alerted him William was missing.

Mr Savage says the 30-second chat outside the woman's home involved her telling him William's foster mother had gone in to make or have a cup of coffee and then noticed the boy wasn't there.

"I'm pretty sure that's what she said," Mr Savage told the inquest.

"That must have been something that I remembered. It might not be right."

Pressed on how strong his recollection was, he said: "I still think that happened but I can't guarantee it. I'm not going to guarantee something I'm not sure about it."

Mr Savage also wavered from previous statements when telling the inquest he'd inspected two deep stormwater drains during his initial solo search in bushland, and that he couldn't remember seeing the foster father crying and upset inside the foster grandmother's home before the search.

After scouring the bush for up to 45 minutes on a path that took him to his backyard, Mr Savage did not inform anyone his search had found nothing, the inquest was told.

"I walked out the front just to see what was happening and then I went back inside," he said.

"I see the police (were) already there. I thought 'That's the police, they don't need me'."

He said he made himself some food and tea because he thought whether he spent the day searching or making the long drive to see his brother in Casino he "should do it on a full stomach".

The inquest was told one of Mr Savage's statements mentioned friends unexpectedly arriving after he made himself a tea but those friends said they didn't arrive until 1.20pm.

Mr Savage said he must have spent the intervening time "keeping an eye" on the search.

The elderly man told the inquest before William went missing he'd sat on his veranda with toast and tea between 9am and 9.30am and could hear children playing.

He was unsure whether his late wife, Heather, was with him.

"I remember hearing the kids."

Mr Savage's phone records show he made a phone call to his brother in the Casino hospital from 10am until 10.08am.

In a police video filmed in 2017 and shown to the inquest on Thursday, Mr Savage says he planned to make the four-hour drive to Casino to pick his brother up later that day and the call was likely in relation to that.

His wife left for bingo at 10.37am and within 15 minutes he was back inside making another round of tea and toast, Mr Savage said.

That's when a neighbour knocked on his door and alerted him to William's disappearance.

Mr Savage says he went across the road, spoke briefly with William's foster grandmother and saw the foster father inside the home.

He couldn't recall hearing anyone calling out William's name. The inquest continues.

Australian Associated Press