Coroner Harriet Grahame was to hand down her long-awaited findings on June 18 after the two-year inquest but has now scrapped that date.

Counsel assisting the coroner, Gerard Craddock SC, was to file and serve by this Friday his submissions on the evidence about the three-year-old's disappearance in 2014 from his foster grandmother's home in Kendall, NSW.

Mr Craddock will now have until April 30.

"Further orders in regard to the timetable for submissions and the delivery of Her Honour's findings will be made in due course," a court spokesman said in a statement late on Tuesday.

The inquest into William's disappearance began in March 2019, with the fourth and final round of hearings ending in October 2020.

Scores of witnesses, including detectives, Kendall locals and convicted criminals, were questioned during the hearings while reams of documentary evidence were put before the coroner.

Jailed sex offender Frank Abbott became a particular focus, with witnesses claiming Abbott knew "something" and had been "obsessed" with the search for William.

The now-elderly man lived a caravan on a property on Herons Creek Road, about four kilometres from Kendall, at the time of the boy's disappearance.

He denies any involvement and has suggested the finger was pointed at him because of his criminal history and the reward money.

The lead police investigator has said new information, not police resources or more reward money, was needed to progress the investigation into William's disappearance further.

As of October, police still hadn't determined how the boy went missing while playing at his foster grandmother's home in Kendall on the NSW mid-north coast on September 12, 2014.

Despite police being called within the hour, hundreds of persons of interest being investigated, dozens of searches and stacks of evidence documented, no trace of the boy or his Spider-Man suit he was wearing has been found.

Australian Associated Press