[3] Although having volunteered for military service in the First World War, Heffron was rejected on medical grounds, with the attending doctor citing heart troubles.

However, the rejection on the grounds of health was done despite an allegation that Heffron, in an attempt to encourage such a finding, had smoked 12 packs of cigarettes prior to his medical, in order to avoid military service.

[4] His elder brother, William Thomas Heffron, enlisted as a private on 3 October 1917 and was killed in action a few days before the armistice on 4 November 1918, while serving with the 1st Battalion, Auckland Infantry Regiment.

That same year in Victoria, Heffron was appointed an organiser for the Federated Clothing Trades of the Commonwealth of Australia and also joined the leftist Victorian Socialist Party.

In June 1939, three other MPs, Frank Burke (Newtown), Mat Davidson (Cobar) and Ted Horsington (Sturt), unhappy with Lang's leadership joined the ILP.

As a result of its success, John Curtin and the federal executive of the ALP pressured the NSW ALP to readmit Heffron and his party at a unity conference at the Majestic Theatre in Newtown on 26 August 1939[12] Heffron then combined forces with William McKell to depose Lang on 5 September 1939, with McKell becoming the new leader of the party, although he declined to stand for the position of deputy leader.

[14] In this role he was responsible for the civil defence and air-raid precautions of New South Wales, which became increasingly more important after the entry of Japan in the Second World War in December 1941 and subsequent attacks on Australia on Darwin and Sydney in 1942.

[17] As minister during the important post-war era of economic growth and infrastructure development, Heffron presided over the expansion in the number and facilities of the public schools in NSW, with enrolments in all areas doubling in size.

[19] Heffron's reformist attitude in education also extended to the tertiary level, in which he intended to significantly expand NSW's capacity for higher-level learning.

[2] At the ballot on 5 February 1947, Heffron lost by two votes to the Minister for Housing, James McGirr, who was favoured by the more Catholic and conservative caucus members.

When McGirr announced his resignation on the grounds of ill health on 1 April 1952, Heffron put himself forward as a candidate to succeed him against, among others, Deputy Premier Joseph Cahill.

In parliament, Heffron tended to reflect this by leaving most of the speaking roles to his deputy Jack Renshaw and local government and highways minister Pat Hills.

In an age where clichés cloak most politicians, Heffron throws them out as though they were devastating retorts, although occasionally the old radical has shown his teeth, flashed into anger, and for a few minutes reminded us that this was the great mob-orator who led many bitter strikes.

On 14 October 1960, Heffron presided over the official opening of Warragamba Dam, the completion of which meant that it became the primary reservoir and the first reliable water supply for the whole Sydney catchment.

[37][38] In early 1961, in response to lobbying from Lend Lease Corporation, Heffron's government (led by Minister for Justice, Jack Mannix) undertook a significant groundbreaking reform for apartment buildings by introducing Strata title schemes, the first such system in the world, which enabled separate ownership of units outside of company and co-operative titles and allowed for unit owners to more easily gain finance and loans.

[40]In January 1960 Heffron provided his old friend H. V. Evatt a dignified exit from federal politics by nominating him to succeed Sir Kenneth Street as Chief Justice of New South Wales.

[41] Downing's concerns came to pass as Evatt indeed proved highly ineffective, often wracked by mental and physical ill-health, was reduced to having most of his judgements written or co-written for him, and resigning in 1962 after only two years as chief justice.

[42] Upon his elevation as premier Heffron, following an approved motion from the 1958 state conference, reanimated the longstanding Labor policy to abolish the Legislative Council of New South Wales by announcing a statewide referendum on this question.

[44] In the case of Clayton v. Heffron (1960) a majority of the full bench of the Supreme Court of New South Wales (headed by Chief Justice Evatt) found in favour of the government four to one on the grounds that they had complied fully with the intention of section 5B.

[46] In January 1961, Heffron announced the date of the referendum for 29 April 1961 and affirmed that it would be a simple yes/no question and would not include "alternative proposals such as retaining the Upper House on an elective basis".

[52] At the 1962 election Heffron, despite the damage to prestige represented by the failed referendum, put forward new policies including the establishment of a Department of Industrial Development to reduce unemployment, free school travel, aid to home buyers and commencing the construction of the Sydney–Newcastle Freeway as a toll-road.

[53] At the election the Labor Party increased its margin by 5 seats, leaving a comfortable majority in the new parliament, although its success was attributed to the unpopularity at the time of Sir Robert Menzies' federal Liberal government following the 1961 credit squeeze.

[56] Heffron and Renshaw backed down on this last provision, leaving no state aid for Catholic schools, and affirming the dominance of the Federal party in such matters.

His announcement came as a surprise to many members of his own party, although there had been existing hints in the previous months that the Labor caucus had been discussing a departure plan for Heffron, to be replaced by the Deputy Premier Renshaw.

[56] Having been embarrassed when addressed as "Excellency" on an overseas trip as Minister for Education in 1954, Heffron was nevertheless granted by Queen Elizabeth II retention of the title "The Honourable" on 24 June 1964 for having served for more than three years as a member of the Executive Council of New South Wales.

After resigning as premier, Heffron remained in Parliament as member for Maroubra, retaining his seat at the 1965 election, thereby witnessing his Labor Party enter opposition for the first time in twenty-five years.

[2] In his later years he became more attached to the beliefs of his youth, and became the first Australian statesman to be received by Pope Paul VI during an official visit to the Vatican in July 1963.

It is, in consequence, not surprising that under his ministerial aegis we see the results of his educational zeal and enthusiasm in the rapid growth of the Child Welfare Department, which he has raised to a level equal to the best overseas, in the expansion of library and other cultural facilities, in the planning and creation of new schools, colleges and institutes of higher learning, and last, but not least, in the unfailing sympathy he has always shown with our own University and in his ready understanding of its more pressing problems.

"Heffron was also awarded an Honorary Doctor of Science at the New South Wales University of Technology's first graduation ceremony to be held on the Kensington campus on 16 April 1955.

[20] In 1956 his portrait, depicting him in the Scarlet and Old Gold robes of his honorary D.Sc., was painted by Henry Hanke, entered into that year's Archibald Prize, and was purchased by the university for its collection in 1957.