After twice failing to topple what is now Australia’s last surviving state Labor government despite winning clear majorities of the statewide vote, the sense of grievance among South Australia’s Liberals shows no sign of abating.

Speaking at the state branch’s annual general meeting in Adelaide on Saturday, party president Robert Lawson complained that the re-election of Jay Weatherill’s government on March 15 was an “undemocratic and illegitimate result“, and foreshadowed a legislative push to redress the present system’s clear bias to Labor.

Adding insult to injury for the Liberals is the unique provision in South Australia’s electoral legislation that directs the boundaries commissioners to aim for “electoral fairness” when they redraw the map between each election, preferably by creating a situation in which a two-party vote majority converts to a majority of seats in the event of a uniform swing. When it failed to play out that way in 2010, the commissioners took the view that the imbalances produced by a wildly uneven and, from Labor’s perspective, remarkably fortuitous pattern of swings were likely to even out the next time around. They didn’t, and the Liberals were once again left champing at the bit as Labor held firm in decisive marginal seats in Adelaide.

The problem the Liberal Party faces in South Australia is that too much of its vote is locked up in rock-solid rural and regional seats. With the decline of the industrial “iron triangle” centres of Whyalla, Port Augusta and Port Pirie, only the former now gives Labor enough of a support base to sustain a seat for it outside Adelaide, the best efforts of the carbon tax notwithstanding. In no other regional seat is Labor seriously competitive; the four biggest margins in the state are Liberal seats in rural areas. Meanwhile, on the more even electoral terrain of Adelaide, Labor has emerged ascendant across a range of suburban seats held on comparatively modest margins.

The Liberal Party’s big idea to address the problem, articulated again on Saturday by Lawson, is for the members elected to the lower house to be supplemented as necessary by “a top-up system, under which a party which receives 50% plus one is allocated sufficient additional members to enable it to form government”.

Without wishing to diminish the Liberals’ entirely understandable dissatisfaction with the status quo, I can’t help thinking that South Australia isn’t missing much if this is the best they can do.

“There can be little doubt that the election’s failure to produce a change of government was out of line with community expectations.”

If one is to accept the logic of the Westminster system, through which government is comprised of the elected delegates of geographically defined communities, the results of the last two elections were as good as any other. Clearly, though, the Liberal Party does not accept this logic in any meaningful way, and in this it’s very far from alone.

There can be little doubt that the election’s failure to produce a change of government was out of line with community expectations. It is no less clear that a majority of the Australian electorate frowns upon minority government, the other regularly recurring consequence of the existing system that top-up seats would presumably do away with. But the Liberals, through a combination of timidity and conservative sentimentality for 19th-century British constitutional forms, would apparently prefer to bastardise the existing system than follow their principles through to their logical conclusions.

My advice to the Liberal Party, in the unlikely event that it should wish to hear it, is that a rare confluence of self-interest and public receptiveness to reform has granted it an opportunity to think big, and in doing so to demonstrate to a sceptical electorate that it is still a party of ideas.

If it is to be granted that government formation should be a matter of a majority vote, there is no point in tethering it to the confidence of a stacked parliament. It would make far more sense to follow the American example, in which a chief executive is directly elected for a fixed term and required to negotiate the passage of laws and the budget with the legislature.

In Australia, the normal pattern is for an upper house chosen through proportional representation to serve as a check on an executive that maintains an iron grip on the lower house through party discipline and a majoritarian electoral system. If it’s already unclear what real purpose the lower house serves in this circumstance, a presidential-style executive would definitively render it redundant. The way would thus be open for a second sweeping and potentially very popular reform, namely the abolition of one of the two chambers of parliament.

To ensure that the remaining chamber does indeed serve as a brake on the executive, and also for the sake of genuine representativeness, its method of election should be proportional representation. As the mixed-member systems of New Zealand and Germany illustrate, this need not entail doing away with local representatives, who can be topped up in the chamber with party list MPs as required to achieve a proportional result.

If that sounds a forlorn dream, so too is the Liberal plan, at least for now. Labor has been justifying the March election result by dismissing the two-party preferred vote as a “mathematical construct”, and is unlikely to find the appetite to reform a system that has lately served it so very well.

Realistically, the ball is in the court of the boundaries commissioners. Next year, they will again be required to redraw the electoral map, keeping in mind the ultimately non-binding direction that they should do so with an eye to the fairness of the previous election result. This time around, the pressure to torture the boundaries to the advantage of a twice-jilted Liberal Party is likely to prove irresistible.