The mystery of the Beaumont children’s disappearance remains one of Australia’s most perplexing cold cases.

These siblings, aged between four and nine, vanished on Australia Day in 1966 after setting off for Glenelg Beach on a bus at 8:45 a.m.

They were expected back home by noon. However, as the buses arrived at 12 p.m. and then 2 p.m. without the children, unease turned into alarm.

Concerned, their father, Grant “Jim” Beaumont, headed to the beach that afternoon to search for them, but found no trace of his children.

Later that evening, both Jim and their mother, Nancy Beaumont, reported the children missing to the police.

That evening, he and their mother Nancy Beaumont reported the disappearance to police.

The case sparked a furore in the public and the media, while investigations established that the children had been seen with a tall man who had light brown or fair hair, believed to be aged in his mid-30s.

His identity has never been established.

Despite reported sightings and hoax letters in the intervening years, the children have never been reliably seen again.

The disappearance of the Beaumont children is seen as having prompted a change in Australian lifestyles, with parents subsequently unwilling to let their children play independently or out of sight.

As of 2018, a $1 million reward remains posted for any information leading to the resolution of the case.