The Yarra River neatly divides Melbourne in two: the north and west, which (until the coming of the Greens) psephologists never had to worry about, and the south and east, where all the electoral action is.

The latter can in turn be broken down into three distinct areas. The affluent strip along the south bank of the Yarra and stretching down the coast to about Beaumaris consists mostly of safe Liberal seats. The territory further out divides roughly in half between eastern and south-eastern suburbs, along a line that isn’t obvious on a map but is intuitively clear to locals (you can think of it as the Monash Freeway and the northern edge of the City of Casey).

Today we will consider the 12 seats making up the eastern suburbs.

This is historically Liberal territory; Labor’s failure to make up ground here kept it out of office until 1982, and the Liberals again held every seat in 1992 and 1996. Labor then won two seats in by-elections — Mitcham (1997) and Burwood (1999) — but the area otherwise held firm for the Liberals at the 1999 election, even though Labor made enough gains elsewhere to narrowly win government.

The landslide came in 2002, when Labor swept the eastern suburbs with swings of up to 12%, leaving the Liberals with just three seats — Box Hill, Warrandyte and Scoresby. In 2006 they recovered to some extent, winning back Bayswater, Evelyn and what are now their two most marginal seats, Kilsyth (0.4%) and Ferntree Gully (0.04%).

Labor’s remaining five seats are now all in the firing line: Mount Waverley (0.3%), Forest Hill (0.8%), Mitcham (2.0%), Burwood (3.7%) and Monbulk (6.7%). Rationally one would expect them to have already written off the first two — except that this is an area that typically doesn’t swing much (which is why the 2002 result was so exceptional), and sitting members are hard to dislodge.

Most expected Mount Waverley to go last time as well, but Labor’s Maxine Morand narrowly hung on. Forest Hill and Mitcham swung more, and may complete the process this year. Burwood and Monbulk — at (respectively) the western and eastern ends of the area — will be more interesting.

Monbulk was noteworthy in 2006 for recording the highest Greens vote outside of the inner suburbs, 16.2%. One might infer that the Liberals’ decision to declare war on the Greens will not go down particularly well there.

The Liberals also have to defend their own seats; it would make sense for Labor to try to distract them by throwing some money at a seat such as Ferntree Gully, which was decided in 2006 by just 27 votes. A lot of Liberal resources last time went into shoring up their sitting members (with hindsight far too much, since they all won comfortably, although it was an understandable mistake in light of the 2006 experience). But newly elected sitting members can nearly always count on a swing in their favour, so even Ferntree Gully and Kilsyth should be off the doubtful list.

If there was one word to sum up the whole area, it would be “conservative”. The majority are natural Liberal voters — areas such as Croydon, Glen Waverley and Scoresby have some serious money, and even many of the poorer areas are strikingly monocultural — but they also have a strong predisposition towards backing the government, as long as it’s not seen to be mismanaging things too badly.

That’s probably why they swung to Labor in the recent federal election, and didn’t fully meet Ted Baillieu’s hopes in 2006. Whether they will this time will depend more than anything on whether they see the Brumby government as having gone off the rails, or still being a safe pair of hands for the next four years.