Before the campaign has had the chance to begin in earnest, it seems that the Victorian election is already done and dusted. On November 29, Premier Denis Napthine stands to suffer a defeat such as the Liberal Party hasn’t known since the Steve Bracks landslide of 2002, making him the first Australian Premier to lead a first-term government to defeat since Rob Borbidge was dumped amid Queensland’s One Nation revolt in 1998.

That, at least, is the impression you’ll receive if you pick up today’s Age, in which Fairfax’s newly acquired pollster Ipsos opens its account with a Victorian state poll showing Labor with a surely insurmountable lead of 56-44 on two-party preferred.

However, this result is something of a puzzle, in being the odd man out in a crowded Victorian market over the past few days — Galaxy, Essential Research, ReachTEL and Morgan all having proved of one mind in showing Labor’s lead in the range of 52-48 to 53-47.

Despite the apparent peculiarity of its result, Ipsos is not to be lightly dismissed, its lack of local match practice notwithstanding. The company is one of the world’s largest market research concerns, and the poll is as sturdy as they come in terms of sample size (1400 respondents) and methodology (live interview phone polling targeting both landlines and mobiles).

On closer inspection, the poll proves to be less distinctive than it first appears. Despite the apocalyptic two-party result, the Coalition actually has a lead on the primary vote of 39% to Labor’s 37%, which in both cases is within a single point of Galaxy, Essential Research and ReachTEL.

Things get a little curious with the Greens’ 17% share of the vote, which would blow the lid off their previous best result of 11.2% at the 2010 election. Galaxy, Essential Research and ReachTEL all had the Greens in the more intuitively believable range of 12% to 13.3%, although Morgan’s SMS poll muddied the waters with a result of 18.5% — something credited at the time only by cock-eyed Greens optimists (not that there’s ever much shortage of those). Unlike Ipsos, Morgan’s overshoot for the Greens was matched by a lower Labor vote of 34%, so that the two cancelled out to produce a two-party preferred result well in line with the others.

However, the larger part of Ipsos’ peculiarity relates to the vexed question of preference distribution. The industry standard these days for calculating two-party preferred is to assume that minor party and independent preferences will divide between the major parties in the same way as at the previous election. This is, at best, a little inelegant, in that preference flows are in practice variable to at least some extent, particularly when a significant new minor party arrives on the scene. However, the alternative approach of asking minor party and independent supporters how they will direct their preference is blighted by the influence of how-to-vote cards that aren’t available to the opinion poll respondent.

Ipsos did in fact produce a second two-party result for its poll that followed the more conventional method, and it had a more conventional result of 53-47. The Fairfax papers usually (though not always) favoured this method when presented with two sets of results by its old pollster, Nielsen — but this time, it seems, it went for the bigger headline.

This is not to say that the unusual extent to which minor party supporters are telling pollsters they favour Labor over the Coalition is of no consequence. For one thing, it may reflect a positive response by Greens supporters to Labor’s position on the East West Link, and this may indeed translate into a dividend for Labor when the Greens’ apparently healthy share of the vote is distributed as preferences.

Another reason to doubt the utility of preference allocation on 2010 election figures is that flows to Labor on that occasion were unusually weak. At last year’s federal election, Labor received nearly 86% of Greens preferences in Victoria, and over 51% of those from all other minor parties and independents combined. State electoral commissions don’t publish preference data in the same detail, but it seems the equivalent figures in 2010 were more like 80% and 40%.

The troubling implication for the Coalition is that this week’s spate of headline poll results, which have been quite daunting enough, have actually flattered it a little — perhaps to the tune of a full percentage point on two-party preferred.

As difficult as their position may appear, the Coalition won’t be giving up hope quite yet. Napthine’s personal ratings appear to have improved relative to those of Opposition Leader Daniel Andrews, and the change has coincided with Labor’s politically risky decision to scrap the East West Link. Despite showing a strong lead to Labor, ReachTEL’s poll found 47.7% in favour of the project, with only 29.5% opposed.

The challenge facing the Coalition over the next month is to finesse that sentiment into hard support from voters who presently seem more concerned with sending a message to Prime Minister Tony Abbott.