Precedents, unless they are broken, are important. And there is very much a precedent in this instance. For the sake of pithiness it can be called the Gorton precedent of 1969.

There was a federal election in Australia on October 25, 1969. Prime minister John Gorton led the incumbent Liberal-Country Party coalition government. Labor, in opposition since 1949 and badly beaten in a khaki (think Vietnam) election in 1966, was led by Gough Whitlam.

And then came 1969.

Australian elections are usually prosaic affairs but the 1969 election was different. It is one of the few Australian elections to inspire a popular work of literature.

David Williamson's play Don's Party immortalises the election night mood swings among a group of youngish newly educated Labor voters who worshipped Whitlam.

Early on in the night the mood was euphoric. It appeared for a while that the modernising idol had defeated the Liberals.

Then things tightened. For a glorious fleeting moment it seemed that the nation would end up with a hung parliament with the balance of power being held by a lone independent from Tasmania (Michael Townley).

In the cold light of day though drab reality kicked in for the people in Don's Party and for actual Labor voters across the nation.

The Gorton government ended up being re-elected with a greatly reduced but still eminently workable majority in the House of Representatives.

The nation, as it had done over the past twenty years, had opted for the Liberals.

But the drama was not over. A final act not written by David Williamson was in train.

After each federal election the victorious party room - the Liberals in the case of 1969 - convenes in Canberra to rubber stamp the incumbency of its parliamentary leader.

But this ritual did not happen in 1969.

Prime minister Gorton had by this time lost too much political skin for comfort.

He had inherited a huge lower house majority on becoming prime minister after Harold Holt went missing in 1967. But his aura soon dwindled. He was eager to break away from the lingering unnationalistic drowsiness of the 1950s and yet seemed to have no coherent and strategic reform agenda. He got the media and public servants offside. He annoyed the state premiers and vexed important members in his own party. He was unfocused and Whitlam was not.

1969's loss of seats - though not of power - alarmed the internal Liberal critics. Whitlam, having revived Labor, seemed to have the drop on Gorton. Though just re-elected, Gorton obviously had to go for the sake of longer-term viability. The sooner the better.

The would-be coup was all the more tempting because there was no need to agitate for a spill of the position before moving on to the leadership ballot itself. A vote on the leadership was always the first item of party room business after an election.

On October 30, five days after the 1969 election, a dissatisfied cabinet minister (David Fairbairn) stated that he was considering contesting the leadership. He declared his candidacy a few days later. The treasurer Billy McMahon thereupon also announced his candidacy, deputy prime minister John McEwen having indicated that he no longer rejected the, for him till then, ridiculous notion of a McMahon prime ministership.

The date of the party room meeting to decide the matter was fixed for November 7.

The Australian people had no say whatsoever in the resulting election for prime minister but they were not overly vexed. Their attention was fixed elsewhere. The party room contest after all took place in the same week in which the 1969 Melbourne Cup race was run (Rain Lover won.)

The party room ballot went ahead towards the end of Cup week. Gorton survived. His biographer Ian Hancock considers that in all probability "Gorton won an absolute majority of between one and five votes" in a party room comprising 65 Liberals.

So close to half his parliamentary party voted against a man who had won a federal election barely a fortnight earlier.

As Barry Jones noted in a letter of congratulations, Gorton's defeat would have rendered the democratic process of the election meaningless.

But Jones was a Labor person, an outsider. There had been a challenge. The Liberals had not questioned the legitimacy of dumping a newly re-elected prime minister. They took it for granted that they had a right to do so but decided, in 1969, not to exercise this right.

What happened under Gorton demonstrates that a freshly re-elected Prime Minister can still face the prospect of an immediate post-election party room challenge if the victory is judged to be too modest.

Nothing much has changed since 1969. After May 21, the Liberal party room will again have the question of leadership as its first item of business. For the incumbent the occasion is usually non-dramatic. After a clear victory the incumbent is rubberstamped. After a clear defeat the leader is expected to gracefully stand down.

But there can be ambiguity. The outcome of the forthcoming election is widely expected to be tight. It is well known that Scott Morrison has senior cabinet colleagues who are ready and willing to take over at a moment's notice.

Against this uncertain background there may well be senior Liberals willing to pursue the Gorton-era option should the circumstances arise.

The events of 1969 show that any attempted post-election change of leadership would go ahead without being weighed down by any suggestion that somehow the will of the electorate at large was being ignored or disrespected.

Existing mechanisms and a half-forgotten but still relevant precedent may make for an interesting experience for the Prime Minister after the people speak on May 21. 1969 shows that theirs may well not be the final word in deciding who is to end up as our Prime Minister.