On This Day: Australian PM is presumed drowned after going swimming

December 17: Australian Prime Minister Harold Holt vanished and was presumed drowned after going swimming on this day in 1967.

The 59-year-old disappeared off Cheviot Beach at Portsea, Victoria only 22 months into his time in office.

The Australian Government announced that Holt was officially presumed dead after two days of one of the biggest sea searches in history.

It sparked a leadership crisis in his Liberal Party and a host of conspiracy theories, including claims he was a Chinese spy and had been picked up by a submarine.

His body was never found and he was only officially declared dead at an inquest held in 2005.

Yet a memorial service in Melbourne, where Holt lived and had begun his law career before being elected at MP for one of its suburbs, was held on December 22, 1967.

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A British Pathé newsreel shows the Prince of Wales, then aged only 19, joining UK Prime Minister Harold Wilson and Tory leader Ted Heath on a plane at Heathrow.

U.S. President Lyndon B Johnson – for whom Holt coined the slogan “All the way with LBJ” after committing Australian troops in Vietnam, also attended the service.

A year earlier, Holt ensured Johnson was the first American head of state to visit Australia after becoming his strongest ally in the controversial U.S.-led war.

He also relaxed “White Australia” immigration policies, gave Aborigines equal rights, decimalised his country’s currency and refused to follow Britain’s pound devaluation.

Holt also became embroiled in a scandal over misuse of government aircraft when his party rival John Gorton revealed how the PM misled Parliament over the issue.

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Yet he is today best remembered for his unfortunate disappearance.

Holt, an experienced diver, had driven with friends to one of his favourite snorkelling spots to watch British yachtsman Alec Rose sail by while circumnavigating the globe.

Despite suffering a recent shoulder injury – and being advised by his doctor not to go swimming – he ignored his group’s pleas and took a dip in Port Phillip Bay.

The surf was heavy and the spot, which lies on the tip of the Mornington Peninsula, around 60 miles south of Melbourne, is notorious for strong currents and rip tides.

And he soon disappearing from view, prompting his friends to raise the alarm.

But despite thousands of personnel from the Royal Australian Navy, Air Force and Army searching, they could find no trace of the prime minister.

Despite accounts of Holt’s “incredible powers of endurance underwater”, there had been worries about the leader of the Liberals, who later selected Gorton as PM.

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Aside from his shoulder injury, he had collapsed in Parliament earlier in the year – citing a “vitamin deficiency” but raising fears he might have a heart condition.

His biographer Tom Frame later revealed that Holt had already got into trouble twice while snorkeling earlier in 1967.

On the first occasion, at Portsea in May, he had to be pulled from the water by friends, who found him blue in the face, gasping for breath and vomiting seawater.

There were also suggestions that he was depressed and may have comitted suicide – although this has been firmly denied by family and friends.

It was also claimed that Holt - who allegedly had a series of affairs and met his wife Zara while she was married – faked his death so he could run away with a mistress.

Strangest of all the conspiracy theories was a claim made by British reporter Anthony Grey that he had been a Chinese agent and picked up by one of their submarines.

Fuelling these likely myths was the fact that his body was never found – and, under the law of the state of Victoria, this meant an inquest could not be held.

This was eventually changed in 1985, but it was not until the Victoria Police Missing Persons Unit formally reopened the case in 2003 that an inquest was possible.

On September 2, 2005, a coroner found was that Holt had drowned in accidental circumstances on December 17, 1967.

Among the memorials to the former Prime Minister is the Harold Holt Swim Centre in the Melbourne suburb of Glen Iris.