History against Julie Bishop

History is against Julie Bishop becoming prime minister because in Australia good foreign minsters don't get the top job.

Since the start of the Menzies era only two foreign ministers - or external affairs minister, as the post was called until 1971 - have become PM.

They are the largely unlamented Billy McMahon and, in between his two stints as PM, Kevin Rudd.

Gough Whitlam combined the two for a time.

Yet Australia has had plenty of highly competent foreign ministers who never made it to The Lodge - Percy Spender, Richard Casey, Garfield Barwick, Paul Hasluck, Andrew Peacock, Bill Hayden, Gareth Evans and Alexander Downer.

However, Ms Bishop has already achieved one milestone - being Australia's first female foreign minister.