Amid an otherwise predictable election night on September 7, 2013, the early progress of the count turned up one significant curiosity in the seat of Eden-Monaro, which Labor’s Mike Kelly appeared set to retain even as party colleagues fell around him like ninepins.

With that, a four-decade tradition of invoking the south-eastern New South Wales electorate as a national litmus test finally looked set to come to an end.

As it turned out though, Eden-Monaro wasn’t quite done wielding its magic. Late-reporting booths dramatically turned the tide in favour of Liberal candidate Peter Hendy, and, when the dust had settled, Eden-Monaro had contrived to send a member to the government side of the house for the 17th election in a row.

The enduring mystique of Eden-Monaro has again been evident in the early stages of the present campaign, starting the Friday before last with a report of “shock Liberal polling” from Mark Riley on Seven News.

What the purported internal polling actually showed was that Liberal and Nationals incumbents were leading in seven of eight New South Wales electorates surveyed, albeit by threadbare margins in some cases.

The main reason this wouldn’t have been immediately apparent from Riley’s report is that the exception was “the bellwether seat of Eden-Monaro” — and as Riley and so many others would have it, “where this electorate goes, so does the government”.

Is it indeed the case that a softness in Liberal support in this particular corner of New South Wales portends doom for Malcolm Turnbull? Or is the electorate’s predictive record purely a matter of dumb luck?

Among the sceptics is ABC election guru Antony Green, who has been known to complain of “the tedious line that there is always a seat that goes with government”.

Even so, Eden-Monaro’s diverse mix of elements means there are at least some grounds to argue that it is of deeper interest than just any old marginal seat.

About a quarter of the electorate’s voters are in Queanbeyan, a middle-income slice of suburbia where Canberra spills over into New South Wales.

Further afield, the seat encompasses rural areas whose voters might sooner be represented by the Nationals than the Liberals, along with medium-sized towns such as Cooma and Bega and where Labor remains broadly competitive.

The coastal stretch of the electorate, which runs from south of Batemans Bay to the Victorian border, has also attracted pockets of sea-changers and tree-changers over the years, such that Greens support tops 20% in some booths, while barely registering in others.

The demographic idiosyncrasies of these components largely cancel out in aggregate, leaving the electorate ranked around the middle of the national pack for income, educational attainment, ethnic diversity and percentage of mortgage payers.

Its utility as an electoral barometer is further enhanced by its cohesive identity going back to federation, as its location in the south-eastern corner of the state has spared it large-scale change in the many redistributions over the decades.

Of course, any electorate has its peculiarities, and Eden-Monaro is noteworthy for its preponderance of public servants, and an older-than-average age profile that distinguishes it from the battleground seats on the fringes of the big cities, where young families dominate.

It’s also clear that luck has had a fair bit to do with its uncanny predictive record, with the margin having been inside 1% on four occasions since 1972.

Even if the Eden-Monaro juju isn’t the decisive factor in determining the next inhabitant of The Lodge, the seat is, by any measure, a crucial battleground for the coming election.

The Liberals start the race with a notional advantage over Labor of 2.6%, after receiving a handy 2% boost through an exchange of the Batemans Bay area for interior rural territory in the redistribution.

The sitting member, former Australian Chamber of Commerce and Industry chief executive Peter Hendy, had his profile boosted with a first-term promotion to parliamentary secretary rank late last year — perhaps not coincidentally after he backed the right horse in Malcolm Turnbull’s September leadership challenge.

Hendy’s fealty to Turnbull emerged as an issue last week, when a leaked email from a Liberal Party supporters’ group pointed to a reluctance of conservatives to help with his local campaign, and, in some cases, to a desire to see him lose the seat.

His incumbency advantage stands to be further curtailed by the fact that he will again be opposed by Mike Kelly, the former military legal officer who, after six years as member during the Rudd-Gillard period, is certainly not less well known to constituents than Hendy.

So far the party leaders are yet to make their presence felt in the electorate, with Hendy having to make do with a visit last week from Julie Bishop.

But as long experience has taught them, the voters of Eden-Monaro will come to know the presence of flesh-pressing and baby-kissing political intruders all too well between now and July 2.

*To read more from Crikey‘s William Bowe, visit The Poll Bludger