Nancy Beaumont passed away aged 92 never knowing what happened to nine-year-old Jane, seven-year-old Arnna and four-year-old Grant who vanished on Australia Day.
The youngsters’ disappearance has baffled the country ever since and the case is one of Australia’s most enduring mysteries.
Mrs Beaumont died on Monday at Elder Care Allambi near Glenelg in South Australia.
She and the children’s father Jim Beaumont were no longer married, but both lived close to Somerton Park where the children were brought up in case they ever came home.
On Australia Day 1966, the Beaumont children caught a bus to Glenelg Beach after their parents waved them off.
The children had visited the beach before alone, and Jane was carrying money to buy pies but the children were due home in the early afternoon.
A massive police hunt was launched and there were several alleged sightings of the children around Australia but 53 years later there has been no concrete evidence about their fate.
Dutch psychic Gerard Croiset was flown in to assist with the search, but to no avail.
In February last year, police dug at a possible ‘grave site’ at an Adelaide factory but no human remains were found.
Retired detective Mostyn Matters told Channel 7 that Mr and Mrs Beaumont had left the children’s bedrooms untouched for years in the hope that they might one day be found.