It was through a crackling transistor radio that Sam Holt heard news of a missing VIP at Victoria's Cheviot Beach.
A phone call a short time later confirmed that very important person was his dad, then-Australian prime minister Harold Holt.
On that summer Sunday afternoon in 1967 the Victorian seaside town of Portsea was awash with military vehicles, police cars, ambulances and helicopters.
"I had a feeling of foreboding," Sam Holt said of the flurry of activity around the beach on December 17.
"I heard from a very modern instrument known as a transistor radio that ... there was a missing VIP at Portsea."
Half a century after Holt vanished during a beach swim, the sights and sounds of that day still stick in Sam Holt's memory.
More broadly the tragic disappearance shocked the country, inspired numerous conspiracy theories and overshadowed the political achievements of Australia's 17th prime minister.
"He's remembered as the bloke who drowned," Australian National University political historian Professor Nicholas Brown said.
"But the transition he represented when he took office changed the political landscape."
He made the role of prime minister more informal, developed relationships with the media and was "superb" on television, Brown added.
"He was a modern presence, a much more approachable and affable kind of guy."
During his almost two years as prime minister Holt eased parts of the White Australia Policy, built relations with Asia and backed the referendum to include Aboriginals in the census.
However, Holt also ramped up Australia's commitment to the Vietnam War, including through conscription.
His famous proclamation "all the way with LBJ" while visiting the United States and president Lyndon B Johnson, further inflamed opposition to the war in Australia.
Some conspiracy theories about Holt's disappearance have been linked to his war leadership.
One story famously proposed that the Liberal leader was picked up by a Chinese submarine. Another suggested suicide.
"It was a bad day to go swimming in rough sea and there was no indication he didn't intend to come back," Brown said.
During an address to the Victorian Liberal Party in November Sam Holt called the conspiracies around his father's disappearance "rubbish".
"Harold was not a person who feared for his personal safety, he would swim at places and at times when others wouldn't," he said.
He said his family was honoured by an international delegation including president Johnson who attended a memorial for his father in 1967.
The president comforted Holt's wife Zara and his children after the service.
"He said to us 'Harold was a great man you must always be proud of him'," Sam Holt said.
"And we are."
