Today in History - December 17: Harold ignored doctor's advice and vanished days later

Prime Minister Harold Holt vanished while swimming on December 17, 1966.

Holt was at Cheviot Beach in country Victoria with friends, but only one other went into the water in the rough surf.

His friends said they saw him getting dragged out to sea in a strong undertow.

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Holt was an avid swimmer, snorkeller and skin diver, causing consternation among his staff.

At one point he was cautioned by his press secretary Tony Eggleton about the risks.

"Look Tony, what are the odds of a prime minister being drowned or taken by a shark?" Holt replied.

In the days before his disappearance, Holt's doctor had advised him to swim less.

This advice had been published in The Australian on the day of his death.

Nevertheless, Holt had not reduced his ocean ventures.

He had also refused to take a bodyguard with him when he was on holiday.

His wife later noted that he may have refused a security detail because he did not want witnesses to his extramarital affairs.

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His disappearance sparked a massive search operation, but his body was never found.

His memorial service, held five days later, was attended by Prince Charles, UK Prime Minister Harold Wilson and US President Lyndon Johnson.

In the years following, many conspiracy theories emerged surrounding his death.

Conspiracists believed he was killed by the North Vietnamese or the CIA, or that he faked his death to run away with a mistress.

But the most bizarre theory emerged in 1983.

British journalist Anthony Grey wrote a book with the provocative title "The Prime Minister Was A Spy".

In the book, Grey claimed Holt had been a Chinese agent and had been picked up offshore by a Chinese submarine.

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He purportedly lived the rest of his life in Beijing.

"The whole tale seems to be straight out of fruitcake land," foreign minister Gareth Evans remarked.

China also described the claims as a "sheer fabrication".

Naval experts also noted it would not be possible for a submarine to submerge off the shallow Cheviot Beach.

For more from our Today in History archive, click here

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