A possible grave site for the three missing Beaumont children, who disappeared almost 52 years ago has been uncovered.

Jane, nine, Arnna, seven, and Grant, four, Beaumont disappeared from Glenelg Beach, Adelaide, on Australia Day 1966, never to be seen again despite a major manhunt and one of the nation's biggest ever police investigations.

Over half a century later, a renewed interest in the case has uncovered a site in south east Adelaide where the children may have been buried.

A spokesperson from South Australia Police told Daily Mail Australia results of investigations into land and fresh information from witnesses has led police to examine a new part of the new Castalloy factory in Plympton.

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Jane (right), nine, Arnna (left), seven and Grant (centre), four, disappeared from Adelaide''s Glenelg Beach on Australia Day, 1966 never to be seen again

Results from geophysical tests and new information from witnesses has led police to return to the New Castalloy factory in Plympton (pictured)

The land was searched in 2013, but only a small part of it, and the new search will take place at the back of the plot.

Tests using state of the art machinery revealed a plot of disturbed land on the factory property, measuring about one metre wide, two metres long and two metres deep - the size of a grave,Seven News reported.

Harry Phipps, a deceased Adelaide businessman who was implicated in a book written about the case, The Satin Man, has returned to the forefront of the investigation as a possible suspect, Nine News reported.

He was not named, though enough information was contained in the book for him to be easily identified by those who knew him.

The book alleged he had killed the children and two other men had dug a large hole on the grounds of the factory to bury them in.

Harry Phipps (pictured) owned the factory at the time and was implicated in a book written about the case, published in 2013. In the book, his estranged son claimed he had seen the missing children in their backyard near Glenelg Beach the same day they vanished

Today Tonight named him at the time in a report about the book's contents.

The two men first came forward after images of Mr Phipps were used during a television broadcast.

They told police they had been asked to dig the trench, but neither of them were there when police began to excavate a very small section of the property.

'He was a paedophile, he was a predatorial [sic] paedophile and he was a dangerous man, we know that,' Bill Hayes, a former detective for SA Police told Seven News.

In 2013, Mr Phipps was not a suspect in the case. Major Crime detectives said at the time allegations which implicated him had been investigated and officers chose to leave them.

The factory (pictured) was searched in 2013 following information published in a book on the missing children, but nothing was found

Mr Phipps' estranged son Haydn had earlier claimed to author Alan Whiticker he saw Jane, Arnna and Grant in their backyard in Glenlg on the same day they vanished.

He further claimed his father buried them in the sand pit at the factory, which Mr Phipps owned.

Police say they do not yet have a confirmed date for the excavation, but are expected to begin work in the next few weeks.

Daily Mail Australia has contacted South Australia Police for further comment.



Over half a century later, results of geophysical tests and new testimony from witnesses has lead police to believe they may have uncovered the real grave site of the children

In the coming weeks, officers will return to the site and search a different part of the land, at the rear of the property