The office of deputy prime minister was officially created as a ministerial portfolio in 1968, although the title had been used informally for many years previously.

The unofficial position acquired more significance following the 1922 federal election, which saw the governing Nationalist Party lose its parliamentary majority.

[5] Although no office of that name had officially been created, by 1946 the title "deputy prime minister" was being used in the Commonwealth of Australia Gazette.

McEwen was sworn in as prime minister on the understanding that his commission would continue only so long as it took for the Liberals to elect a new leader.

Governor-General Lord Casey also accepted the view put to him by McEwen that to commission a Liberal temporarily as prime minister would give that person an unfair advantage in the forthcoming party room ballot for the permanent leader.

As it turned out, McMahon did not stand, and Senator John Gorton was elected, replacing McEwen as prime minister on 10 January 1968.

Both Keating and Gillard succeeded incumbent prime ministers who lost the support of their party caucus mid-term.

In November 2007, when the Labor Party won government, Julia Gillard became Australia's first female, and first foreign-born, deputy prime minister.

As part of the 2017–18 Australian parliamentary eligibility crisis, it emerged that the then-incumbent Barnaby Joyce was a citizen of New Zealand by descent (jus sanguinis – by right of blood) at the time of the 2016 federal election.

[2][3] The government immediately issued writs for a by-election for the seat of New England to be held on 2 December 2017, which Joyce won easily.