It's 1998 and Gwyneth Paltrow has just dropped her earring.

She's in a lift, rushing for a train.

In one version of what happens next, the dropped earring means she misses the train and spends months trapped in a dysfunctional relationship.

In a second version she makes the train, discovers her boyfriend's cheating and meets her true love.

That is, of course, the plot (or, more accurately, plots) of the rom-com classic Sliding Doors.

And it's the movie Labor insiders are comparing to their shock defeat at last month's federal election.

Doors opening: mind the gap

In early July last year, the knives were being sharpened for then Labor leader Bill Shorten.

Labor's commanding lead in Newspoll had evaporated and chatter about his leadership was getting loud.

For those in Labor contemplating a change in leader, the Super Saturday byelections in late July was the moment to strike.

Few in the opposition expected Labor to retain the seat of Longman.

Meanwhile, alternative leader Anthony Albanese quietly offered a different vision from the hard line, class-based agenda over which Bill Shorten presided.

On June 22 at the Shellharbour Workers Club, with the by-election just over four weeks away, he gave a speech entitled "Gough Whitlam and the Party of the Fair Go".

Sorry, this video has expired Anthony Albanese urges Labor to engage with business

"We must be brave enough to offer visionary leadership," he said of Labor.

"But smart enough to know that effective reform requires that we bring the people with us."

Those comments seemed then, and even more so now, an indirect criticism of what Mr Albanese's speech described as: "Bold policies ... from Bill Shorten and Chris Bowen."

One Labor source says strategists were so convinced Labor would lose Longman they ordered pre-selections in some seats, anticipating then prime minister Malcolm Turnbull would call a snap election to catch a rookie Labor leader by surprise.

Then came the proverbial dropped earring, a Sliding Doors moment that seemed trivial at the time but which would rewrite political history.

LNP candidate for Longman Trevor Ruthenberg lose the seat of Longman in 2018 after revelations he lied about his service record. ( AAP: Darren England )

Big Trev's dodgy medal

On July 17 the Courier-Mail caught the LNP's candidate for Longman, Trevor "Big Trev" Ruthenberg, in a lie about his service record in the Air Force.

In the parochial, patriotic northern suburbs of Brisbane it was electoral poison.

A week and a half later he lost Longman to Labor's Susan Lamb. At that point, says one Labor insider, "the cues were put back in the rack".

The sliding doors closed. Gwyneth missed the train. Labor stuck with its man, Bill Shorten.

Meanwhile, across the aisle, the Coalition was about to have its own sliding doors moment.

The Liberals dumped Malcolm Turnbull when parliament resumed after Super Saturday.

The sliding doors stayed open. Gywneth made the train. The Coalition found its one true love, the all-conquering Scott Morrison.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 3 minutes 47 seconds 3 m 47 s Bill Shorten concedes defeat

Next station: election defeat

As Labor agonises over the "what ifs" following its election defeat, all tracks led to Longman and Super Saturday.

What if Mr Albanese faced Mr Turnbull in a snap election?

What if Labor dropped Mr Shorten's class warfare strategy and went with Mr Albanese's plan to "bring the people with us"?

This week he was back in Longman, the day after he claimed the Labor leadership.

"I think Labor got some of our positioning wrong," he said on Tuesday during a doorstop at Caboolture in the heart of the electorate.

"I'm not saying that after the event," he continued.

"Go back and look at my Whitlam Oration."

That's the speech he made at the Shellharbour Workers club last June, where he called out Bill Shorten's divisive strategy a month out from the byelection.

It's also a subtle suggestion that Mr Albanese thinks he would have won this year's election.

Newspoll has borne much of the blame for Bill Shorten's false sense of security going into the campaign, but the truth is it never gave the Opposition a convincing lead.

And Labor ignored the one poll that counted: the Longman byelection.

The opposition thought it won there because of Bill Shorten's campaigning skills, not because a bad LNP candidate got caught out in a dumb lie.

Scott Morrison should send Trevor Ruthenberg a case of wine. ( ABC TV )

Much has been written about Scott Morrison's miracle on May 18.

But it was Bill Shorten's Longman miracle that paved the way.

If he hasn't already, Mr Morrison should be sending Trevor Ruthenberg a case of fine wine.

And watch a re-run of Sliding Doors.