Prime Minister Julia Gillard with Quentin Bryce at Government House after being sworn in as Australia s first female Prime Minister.

Prime Minister Julia Gillard with Quentin Bryce at Government House after being sworn in as Australia s first female Prime Minister. Photo: Brendan Esposito

Political commentators have a way of noticing anniversaries and finding thoughts on their meaning. However, a recent anniversary seems to have passed by - noticed only, it seems, by me. September 7 was the second anniversary of Julia Gillard becoming a so-called ''elected'' prime minister.

Gillard became prime minister on the morning of June 24, 2010. A total of 112 Labor caucus members attended and it is worthwhile to speculate on what the numbers would have been if there had been a contest. My estimate (worked out at the time by talking to well-informed Labor officials) is that 90 votes would have been cast for Gillard and 22 for the then prime minister, Kevin Rudd.

Rather than advertise the extent to which his support had collapsed with his colleagues Rudd decided to go without a contest.

A tear wells in eye of the former Prime Minister Kevin Rudd during his press conference on June 24, 2010, after he was deposed by Julia Gillard.

A tear wells in eye of the former Prime Minister Kevin Rudd during his press conference on June 24, 2010, after he was deposed by Julia Gillard. Photo: Andrew Meares

I think of Gillard as the most interesting prime minister we have ever had. After 26 men in the office that June day gave us our first woman. The other interesting feature of Gillard's prime ministership has been the sheer uncertainty at all times of her tenure.

Our most recent general election was held on August 21, 2010. It was our 43rd. It was also one of four very close elections, the other three having been in 1913, 1940 and 1961. The counting of votes and the declaration of seat results were quicker in 2010 than in those earlier years but the ''cliff-hanger'' period was the second-longest ever. Only in 1913 did Australians need to wait longer.

After 17 days of wheeling and dealing Tony Windsor and Rob Oakeshott gave their support to Gillard. On the morning of September 8, 2010, the Sydney Morning Herald, reporting on the events of the previous day, carried a large photo on its front page of a smiling Gillard looking her most attractive. The headline to the story was ''Gillard buys a second shot at power''.

Fast forward to Monday, February 27, this year. The caucus met and this time it did vote. The numbers were 71 for Gillard and 31 for Rudd, the caucus having been reduced by 10 due to election losses.

In the wake of the 2010 election it was conventional for pundits to say: ''This parliament will not last. An early election is inevitable''. I have never bought that. For two years now I have consistently been making four confident predictions. First, the next election will be held on October 26, 2013. Second, there will be no by-election during this, the 43rd Parliament. Third, Gillard will lead Labor into the 2013 election. Fourth, Tony Abbott will lead the Coalition into that election.

As to who will win I have never made any actual prediction, merely varying probability statements. My present statement is a 90 per cent chance for Abbott and a 10 per cent chance for Gillard.

Given the continuing uncertainty about Gillard's tenure I have been counting down the number of prime ministers her length of service has exceeded. There are 10 so far, Frank Forde for eight days in 1945, Earle Page for 20 days in 1939, John McEwen for 23 days in 1967-68, Arthur Fadden for one month and nine days in 1941, Chris Watson for three months and 21 days in 1904, George Reid for 10 months and 18 days in 1904-05, Joseph Cook for one year, two months and 25 days in 1913-14, Billy McMahon for one year, eight months and 25 days in 1971-72, Harold Holt for one year, t10 months and 23 days in 1966-67 and Labor's Jim Scullin during the Depression.

James Henry Scullin was prime minister for two years, two months and 16 days from October 22, 1929 to January 6, 1932.

In terms of greatness I have Gillard tentatively as our 16th greatest prime minister and Rudd at 17th. My order goes thus: Bob Menzies, John Curtin, Alfred Deakin, Andrew Fisher, Bob Hawke, Joe Lyons, Billy Hughes, John Howard, Ben Chifley, Stanley Bruce, Paul Keating, Malcolm Fraser, Gough Whitlam, Edmund Barton, Harold Holt, Julia Gillard and Kevin Rudd.

However, if Gillard were to win the 2013 election I would raise her up to 10th place, one rung below Chifley and ahead of Keating and Whitlam.

I say that because, if she were to win in 2013, the Australian people would then have expressed approval of all her achievements. Instead of that it is very likely that all her achievements will be torn up by Abbott.

I began this article by saying that Gillard is two years an ''elected'' prime minister. There are those who disparage me about this. Such critics assert that one can only be an ''elected'' prime minister if one takes one's party out of Opposition and on to the Treasury benches at a general election.

On that way of looking at it we have had the following ''elected'' prime ministers since Canberra became our national capital. They are, in chronological order: Scullin, Lyons, Curtin, Menzies, Whitlam, Fraser, Hawke, Howard and Rudd.

On the conservative side Lyons served for seven years and three months, Fraser for seven years and four months, Howard for 11½ years and Menzies for just over 16 years in his ''elected'' (second) term.

Only Bob Hawke on the Labor side can match those conservatives. He served for eight years and nine months. If Abbott wins in 2013 he would be the fifth conservative prime minister to be ''elected'' to that office.

So, a final prediction: if he becomes prime minister Abbott will serve for six years, making him the least successful conservative ''elected'' as PM since Canberra became the national capital.

Malcolm Mackerras is Visiting Fellow in the Public Policy Institute, Australian Catholic University, Canberra Campus.