It had been my intention today to write another article as a compare/contrast exercise between the Liberal Party’s recent victories in Tasmania and South Australia. However, the count has been very slow for the South Australian Legislative Council election. Given my desire not to write until an election is fully wrapped up, I am deferring that article. Suffice it to say, however, that both of our least-populous states now have majority Liberal governments.

In South Australia the Liberal Party has 25 of the 47 seats in the House of Assembly. Its share of the two-party preferred vote is 51.9 per cent compared with an even 53 per cent in 2014. In other words there has been a swing to Labor of 1.1 per cent. That the Liberal Party won in March 2018 when it lost in March 2010 and March 2014 simply tells us that the boundaries were unfair in 2010 and 2014. This time the boundaries are eminently fair which gives the Liberals a victory long overdue.

If I have been surprised at the slowness of the SA Legislative Council count, I have been even more surprised at the speed with which federal redistribution committees have produced their proposed new maps for those jurisdictions whose seat entitlement is changing. Due to the fact of Victoria and the ACT growing in population more rapidly than Australia as a whole, Victoria will have 38 seats in 2019 compared with 37 at present. The ACT will have three where it now has two. By contrast, South Australia will have 10 where it now has 11. Consequently, 151 members will be elected to the House of Representatives in 2019 where at present there are 150.

What interest’s people is the politics of the numbers. That interests me too since I draw up a new diagram known as “the Mackerras Pendulum”. These pendulums (of which I have drawn about a hundred over the years) are always shown on the basis of the two-party preferred vote in each electoral division. Consequently, my current one (drawn following the July 2016 federal election) has the number of Coalition supporting members as 79 and the number of Labor supporting members as 71. The Coalition side has 60 Liberals and 16 Nationals as a majority. However, it also has three independent members on the Coalition side, in the seats of Indi (Victoria), Kennedy (Queensland) and Mayo (SA) since there was a Coalition majority of the two-party preferred vote in those seats.

The redistributions for South Australia and the ACT have turned out exactly as I expected. Labor has lost a seat by the abolition of Port Adelaide, but gained one by the creation of a third Labor seat in the ACT. Victoria, by contrast, has been highly controversial. The effect is that the Coalition has lost its absolute majority. On the Coalition side of my new pendulum there are 77 seats compared with 74 on the Labor side. The majority, in other words, has been cut from eight to three.

The reason is that the new Victorian seat is in the western suburbs of Melbourne and will be safely Labor. In addition, however, the committee has changed the Liberal Party’s share of the two-party preferred vote in Dunkley from 51.4 per cent down to 48.3 per cent while in Corangamite they have changed it from 53.1 per cent down to 49.9 per cent. In addition, they have made the totally stupid proposal to change the name of Corangamite to Cox. 

Consequently the new median seat on my pendulum will be Gilmore on the NSW south coast where Labor needs a swing of 0.8 per cent to win. The current pendulum has Robertson on the NSW central coast as the median seat where Labor needs a swing of 1.2 per cent to win. These may sound like trivial differences but the point is that they add further doubts as to whether the Turnbull government can win the next election. 

The election of Donald Trump to the US presidency in November 2016 left egg on the face of virtually every pundit. It has made me cautious about Australia also. Consequently, I shall predict our election date and make a probability statement about the result. My prediction is that the date will be Saturday 18 May 2019. Consequently we shall know the name of the prime minister by July next year. My assessment is that there are three chances Bill Shorten will be that prime minister for every one chance it will be Malcolm Turnbull.

(Malcolm Mackerras is Honorary Fellow of Australian Catholic University. malcolm.mackerras@acu.edu.au)