In its issue of Saturday 15^th December 1984, The Australian (Surry Hills, New South Wales) quoted the lawyer, judge and Labor politician James McClelland (1915-1999) as defining the Australian-English phrase the politics of the warm inner glow, and as claiming to have coined it:

A few years ago when I was a practising politician I coined a phrase to describe the philosophy of those for whom the ultimate test of a policy is the feeling of personal virtuousness to be derived from its espousal: the politics of the warm inner glow.

The text containing the earliest occurrence of the politics of the warm inner glow that I have found seems that to indicate the phrase was already in common usage at that time—at least within the Australian Labor Party (ALP). This text is Rebuff for Labor Left on party objective, by Michelle Grattan, published in The Age (Melbourne, Victoria) of Tuesday 28^th July 1981:

The ALP yesterday narrowly rejected an attempt to swing the party strongly to the Left on its socialist objective.
In a victory for the party Leader, Mr Hayden ¹, the national conference defeated 28 to 22 a move to sharpen the party’s commitment to socialisation. Mr Hayden warned that such a move would be electoral suicide.
[…]
Mr Hayden warned the conference: “We are, as too often happens with the Labor Party, in danger of confusing the politics of the warm inner glow with the inspiration of the light on the hill. If we do that, we will get badly scorched by the electorate—and not just once but repeatedly.”

¹ William Hayden (born 1933) was the leader of the Australian Labor Party from 1977 to 1983.

Interestingly, in the text containing the second-earliest occurrence of the politics of the warm inner glow that I have found, it is a left-wing member of the New South Wales ALP who uses the phrase against a policy supported by the right-wing rulers of the party. This text is Cavalier leads the counter-charge against women, by Mike Steketee, published in The Sydney Morning Herald (Sydney, New South Wales) of Saturday 22^nd May 1982:

Last year, […] the National Conference agreed that women should comprise 25 per cent of State delegations to future National Conferences. As only about 30 per cent of ALP members at present are women, this constituted a significant step.
[…]
Up to this point, it was all plain sailing for the women. The ALP Head Office—that is, the ruling right-wing faction—had indicated its support for the changes. Few feathers had been ruffled: after all the Affirmative Action Committee had simply been carrying forward the National Conference resolution.
However, no one had counted on the role of Rodney Cavalier ², MP. Cavalier entered Parliament in 1978 with the reputation of a left-wing firebrand.
[…] Many members of the Right categorised him as being part of the “mad Left.”
[…]
He let his tongue loose on the issue this week. “The marketeers of quotas were very clever to label their package with the euphemism ‘affirmative action’,” he told me.
“That appeals to the politics of the warm inner glow—a factor that should not ever be discounted in Labor politics, especially among the middle class. Add to that a generous helping of male guilt and some colossal doses of male hypocrisy (people who believe that quotas will apply to every position but their own) and it is not surprising that the cause has gone so far.”

² The Labor politician Rodney Cavalier (born 1948) was a member of the New South Wales Legislative Assembly from 1978 to 1988.

The phrase then occurs—and is applied to the ideology of the Australian Labor Party’s left wing—in the column Canberra Spotlight, by Neil O’Reilly, published in The Sun-Herald (Sydney, New South Wales) of Sunday 13^th June 1982:

Prime Minister, Mr Malcolm Fraser ³ received his political baptism in the cold-war era of the 1950s and early sixties.
The instincts he acquired then have always governed his behaviour since as the row over nuclear warships revealed during the week.
Victorian Premier Mr John Cain’s ⁴ plan to declare his State a nuclear-free zone when first announced could have been regarded as what one right-wing Labor cynic in NSW once described as “Politics of the warm inner glow.”
He was commenting on the decision of a left-wing Labor-controlled local council in Sydney declaring its municipality a nuclear-free zone.
“It was quite meaningless but it made the lefties feel good,” he said.
But Mr Fraser didn’t see it that way.
He was quick to declare it as a threat to Australia’s defence and the American alliance.

³ John Malcolm Fraser (1930-2015) was the Prime Minister of Australia from 1975 to 1983, as leader of the Liberal Party.
⁴ John Cain (1931-2019) was the Premier of Victoria from 1982 to 1990, as leader of the Victorian Labor Party.