Two elections, four months apart, in Australia’s two biggest states. Two Coalition victories; one largely unexpected and very narrow, the other completely expected and of gigantic proportions.

But there’s clearly at least one common factor in Victoria and New South Wales: in each case the Liberal leader pitched to the centre, presenting himself as moderate rather than scary, a pragmatist rather than an ideologue. Much the same could be said of the party’s other recent successful leaders: Colin Barnett, who won in Western Australia in 2008, and Isobel Redmond and Will Hodgman, who came frustratingly close on the same day last year in South Australia and Tasmania.

For 10 years, the Liberal brand was poison in state elections. Successive Liberal leaders tried to emulate the success (as they saw it) of John Howard by appealing to the populist right, and apparatchiks from Canberra came out to manage state campaigns in ways that would support the Howard message. They failed miserably: cautious, centrist Labor governments made mincemeat of their shrill-sounding opponents.

But in three years, everything has changed. Howard has gone, the scale of his defeat discredited much of his approach, and Tony Abbott — although he too has been unexpectedly successful in electoral terms — does not have anything like the same influence over his state colleagues. Instead they are free to try being sensible, and surprisingly enough it works.

It will be objected that this is mostly coincidence, that the critical factor is just that Labor state governments have become stale (or worse), the wheel of fortune has turned, and Liberal oppositions would be winning now regardless of what they were doing and who was leading them (I can almost hear Peter Brent saying just that).

But if this is true (and to some extent it probably is), then it makes it even more important for the Liberals to work out where they stand. An opposition can endlessly fudge its policy or philosophical positions by concentrating on attacking the government, but if voters are going to put them into power anyway then they need some direction: they need sensible leaders who know where they want to go and how to bring others with them.

For premier-elect Barry O’Farrell, that’s a particularly acute problem. Labor in New South Wales has been such a soft target that the pressure on him to enunciate a clear agenda from opposition was pretty limited, but in government he will have to take hard decisions while having a very large and diverse parliamentary party to hold together.

It’s not just the size of the Liberal victory that creates the problem, but its breadth, extending far into Labor’s working-class heartland. The need to keep the toiling masses out of political power has historically been the big thing holding the Liberal Party together, but that has never looked so anachronistic as on Saturday night. Without class solidarity, however, what other reason is there to expect the same party to be able to contain, for example, David Clarke and Gladys Berejiklian?

If anyone can pull this off, O’Farrell is probably the man: his fundamental decency and consensus style are underpinned by a shrewd sort of toughness that comes from long experience in his party’s factional snakepit. But even he already looks uncomfortable in spouting Abbott’s command-and-control carbon policies, and the tensions will just get more pronounced as he takes on the mantle of Australia’s senior elected Liberal.

This could be crunch time for the Liberal Party: with its amorphous base, its lack of a common ideology, facing divisive issues in difficult times and with limited spoils to satisfy the ranks of the ambitious, there is a question mark over its ability to remain united. And where New South Wales goes, the rest of the country tends to follow.

On the other hand, the Liberals have a long history of sweeping such problems under the carpet, and they’re likely to keep doing it for as long as they can. Australia’s class-based party system already has 100 years on the clock; one day it will have to bend to social reality, but that day could still be a long way off.