On June 28, 1975, the Australian political scene was rocked by an earthquake without precedent in recent memory. The occasion was a federal byelection for the northern Tasmanian seat of Bass, which had been vacated by the indulgent mid-term retirement of Gough Whitlam’s former deputy prime minister, Lance Barnard. In a seat it had come to take for granted, Labor suffered the rude shock of defeat at the hands of Liberal candidate Kevin Newman, whose son Campbell keeps the family firm in business as Queensland premier. So it was that the Malcolm Fraser-led Coalition felt emboldened to unleash the constitutional crisis that would blast the Whitlam government from office later in the year.

The cause of all the fuss was a swing to the Liberals of 14.3% — slightly less than half that suffered by Barry O’Farrell’s government in Saturday’s byelection for the seat of Miranda in Sydney’s outer south. However, you will search in vain for commentary to the effect that O’Farrell is in twice as tight a spot as was Whitlam was, and with good reason.

The main lesson to be drawn from the contrast between two byelections held nearly four decades apart is to do with changing electoral behaviour, and it’s equally instructive with respect to the hyperbole that followed Labor’s epic defeats of the past two to three years.

Survey data continues to find more than three-quarters of respondents expressing at least some level of identification with one of the major parties, but this is increasingly likely to reflect a sense of belonging to either Left or Right, rather than the working or middle class. Voters who define themselves by what they believe, rather than who they are and where they’re from, face a lower psychological hurdle in defecting from their party of identification, which they tend to do only in the short-term.

When recent circumstances have caused the growing herd of half-loyal swinging voters to stampede in a particular direction, the electoral consequences have been unprecedented — first with the state Labor landslides of the late 1990s and early 2000s, and more recently with the shoe on the other foot in NSW and Queensland.

“There is every possibility that this result will prove to be a false dawn for NSW Labor, particularly if feels fortified to stand by its present unsaleable leader …”

So was Saturday’s result in Miranda anything out of the ordinary? The swing to Labor looks to have been a shade over 26%, and it was unaccompanied by the usual signifiers of a pox-on-both-houses effect — turnout was strong, the informal vote down, and the combined minor party vote was lower than it had been in 2011 (particularly for the Greens, the natural choice for Labor-identifying protest voters, whose vote fell by half).

The reversal eclipsed any suffered by the previous Labor government in its catastrophic final term, when byelections in Penrith, Ryde and Cabramatta produced hitherto unheard of swings of 25.7%, 23.1% and 21.8% (it was perhaps no coincidence that the result in Penrith, located in the heart of the psychologically crucial federal seat of Lindsay, was followed four days later by the coup against Kevin Rudd).

One exculpatory factor for the Liberals is that the Miranda swing came off the inflated base of the 2011 landslide, which was a very different result from Labor’s modest re-election in 2007. Some insight into this is provided by the 16.3% swing Labor picked up at a byelection for the rural seat of Clarence in November 2011, just nine months after the O’Farrell government came to power. This passed largely unremarked at the time, as the Nationals retained the seat by a margin of 15.1%.

Another contributing factor was the circumstances in which the byelection was held, with outgoing member Graham Annesley taking up a position as chief executive of NRL club the Gold Coast Titans. Voters’ lack of appreciation at having their weekend interrupted in such circumstances is clearly intensifying, and seems to be felt especially keenly if it’s their second trip to the polling booth in as many months.

Labor was further boosted by the emergence from retirement of its former member Barry Collier, whose record as a maverick had insulated him from the taint of association with his party’s state branch.

And it would be fascinating to know exactly how much bang Labor got from its buck in having polling booths attended by volunteers from the Fire Brigade Employees Union. Bedecked in helmets and high-visibility gear, they looked like they had come direct from the front-line of the Blue Mountains bushfires, except for t-shirts which read “Stop O’Farrell’s Fire Station Closures” and “Firefighters Say Put The Liberals Last”. The union used the campaign to castigate the government over local fire services, so the coincidence of the byelection with the bushfires proved perversely opportune.

There is every possibility that this result will prove to be a false dawn for NSW Labor, particularly if feels fortified to stand by its present unsaleable leader and otherwise shirk from the introspection by its broader political predicament demands. The party also has further punishment awaiting it before it can hope to recover from its low ebb nationally, with ageing state governments in South Australia and Tasmania facing the voters in March.

Nonetheless, Miranda is clearly a source of encouragement for Labor and of concern for the Coalition, and not just in NSW. Taking the changing nature of the electoral game into account, there is no intrinsic reason to believe Labor’s present malaise is worse than others it has suffered in the past, or that its time in the wilderness need be any longer than the historical norm.