He is best remembered as a leader of the movement against Australian involvement in the Vietnam War, for his affair with Junie Morosi and for his later renunciation of conventional politics.

He soon became a detective and gained notoriety working in a special surveillance team known as "the dogs" shadowing squad, where he was involved in a number of dramatic arrests.

Like many Labor figures of his generation, Cairns spent most of his best years in opposition due to the Coalition's unbroken run in government from 1949 to 1972.

At this time he also lectured on Marxist and socialist history, and taught free seminars in Melbourne for working people who were unable to afford tertiary education.

Early in 1967, the septuagenarian Arthur Calwell retired as Labor leader, and Cairns contested the leadership, but lost to Gough Whitlam.

The following year, when Whitlam briefly offered his resignation as part of his fight against the left wing of the party, Cairns again contested the leadership.

[1] By this time, Cairns, like other left-wing firebrands of his generation such as Clyde Cameron and Tom Uren, strongly supported Whitlam, as they were sober enough to realise Labor would never win power again without policies that appealed to the middle class.

[3] They were initiated by the department of Political Science at Monash University, which was interested in researching the psychological motivations of politicians, but Cairns then continued them privately with Diamond over the course of a year, finding them to be "a voyage of self-discovery.

"[4] Another of Cairns' biographers, Paul Strangio, had noted how, in his interview technique, Diamond successfully "managed to penetrate his subject’s emotional defences.

The predicted violence did not occur and the moral force of the, mainly young, protesters had a major effect on Australian attitudes to the war.

In June, ‘’The Bulletin’’ magazine published a leaked Australian Security Intelligence Organisation document which gave a controversial, highly political view of Cairns.

The political fallout from the leak led the government to act on its 1974 election policy to establish the Royal Commission on Intelligence and Security.

On Christmas Day 1974, while Whitlam was overseas, Cyclone Tracy devastated the city of Darwin, and Cairns as Acting Prime Minister impressed the nation with his sympathetic and decisive leadership.

It was during this period, however, that Cairns hired Junie Morosi as his principal private secretary, and he soon began a relationship with her which would eventually help ruin his career.

Overseas finance ministers, especially in Britain and Europe, faced the same problems at this time, but as few Australians were exposed to the foreign media, the economic credibility of the Whitlam administration suffered.

In late 1974, in an attempt to raise funds for large capital works projects (such as drilling for gas on the north-west shelf between Australia and Timor and constructing a pipeline for transporting the gas down to Eastern Australia), senior ministers Rex Connor and Lionel Murphy, along with Prime Minister Gough Whitlam, began to consider arrangements to borrow approximately US$4,000 million petrodollars from the Middle East.

Cairns first became aware of what was to become known as the "Loans Affair" three days after being appointed Treasurer, on 13 December 1974, when he entered at the end of a meeting of the Labor Party federal executive at the Lodge, the official residence of the Prime Minister in Canberra.

In his capacity as Acting Prime Minister during Gough Whitlam's overseas trip covering late 1974 to early 1975, Cairns arranged a meeting at the Reserve Bank in Canberra attended by various senior officials, including Lionel Murphy and Rex Connor.

This, plus Cairns' pre-existing reservations about the loan, prompted him to discuss the issue once again with Whitlam, who then agreed that Connor's dealings with Khemlani should come to an end.

In 1974, Cairns was introduced by Robert Menzies to George Harris, a Melbourne businessman and president of the Carlton Football Club.

[10] Harris had offered to secure loan funds for the Australian government, and in March 1975 Cairns signed a letter agreeing to a 2.5% commission.

Ironically, opposition politicians, including Malcolm Fraser and a number of his ministers, spoke out in defence of Cairns, agreeing that they too signed letters of which they had little or no memory.

The reports highlighted Morosi's lack of public service experience, past business failures, her physical beauty and pointed out that she had often been seen dining in Canberra with senior Cabinet ministers.

[11] During the Australian Labor Party's National Conference in February 1975, Cairns gave an interview to a reporter in which he spoke of "a kind of love" for Morosi, reigniting the controversy.

[citation needed] The jury in that case found that the article in question did contain "an imputation" that Cairns was "improperly involved with his assistant, Junie Morosi, in a romantic or sexual association", but that this statement was not defamatory.

[12][13] Four years earlier, referring to his decision to employ Morosi and the ensuing media storm that it created — Cairns said that "looking back over it, it was a mistake on my part".

He sponsored a series of Down to Earth conference-festivals, known as ConFests, at various rural locations, and was photographed taking part in Counterculture inspired activities, such as meditation.