Western Australians went to the polls on Saturday to deliver exactly the same verdict on daylight saving as they had in 1975, 1984 and 1991. However, it was a very different story in the West’s other big electoral event of the weekend — the by-election for the state seat of Fremantle, vacated by Labor Left factional titan Jim McGinty.

The result was an historic win for the Greens, whose candidate Adele Carles finished the night with 54 per cent of the two-party vote. This was only the second time the Greens had won a state or federal lower house seat outside of Tasmania, with its Senate-style system of proportional representation.

The first such occasion was in 2002, when Michael Organ defeated Labor’s Sharon Bird in a by-election for the Wollongong-based federal seat of Cunningham. While Carles might not have been first off the block, in many ways her achievement was the more remarkable.

Michael Organ owed his win to internal Labor squabbles which saw the vote scatter among various union-backed independents, allowing him to win from a relatively modest primary vote of 23.0 per cent.Sharon Bird had no trouble recovering the seat for Labor on her second attempt at the 2004 election, when Organ finished third.

Carles by contrast won Fremantle with a handsome primary vote majority of 44.3 per cent to 38.6 per cent, which as Antony Green points out was the first time a Greens candidate had outpolled Labor at a federal, state or territory election.

It’s true that by-elections often produce aberrant results, particularly if as on this occasion one of the two major parties sits on the sidelines. However, Carles’s triumph follows her near-miss at the state election last September, when she fell 642 votes short of overtaking the Liberals and riding over Jim McGinty on their preferences.

Now bolstered by the advantages of incumbency, Carles stands an excellent chance of retaining the seat for the long term.

The result has myriad implications, locally and beyond.

It adds a new element of unpredictability to the already volatile situation in the Legislative Assembly, which now houses 27 Labor members, 24 Liberals, four from a highly assertive National Party, three independents of varying political backgrounds and now one Green.

Labor also faces a renewed round of soul-searching eight months after its ejection from office. Loud grumbling can be heard within party ranks over its recent habit of recruiting candidates from outside the Labor movement — in this case Fremantle mayor Peter Tagliaferri, who it was hoped would stave off defeat by winning over homeless Liberals.

With Labor’s primary vote remaining static, it’s clear that for every such voter gained another was lost due to Tagliaferri’s pro-business orientation as mayor.

There is also renewed scrutiny surrounding the leadership of Eric Ripper, who has generally been perceived as a short-term proposition in any case. His logical replacement would be popular Gallop-Carpenter government minister Alannah MacTiernan, recently said to be harbouring federal ambitions for the Liberal-held seat of Canning.

More broadly, Carles’s win underscores the point that the Greens’ encroachment into inner-city and bohemian enclaves is continuing to gather pace, posing a serious long-term threat to what had traditionally been Labor’s strongholds.

A number of seats in Sydney and Melbourne are likely to fall when the tide goes out on the ageing state Labor governments, which seems particularly imminent in the case of New South Wales.

Federally, Lindsay Tanner’s seat of Melbourne reached a watershed in 2007 when Greens candidate Adam Bandt overtook the Liberal and finished 4.7 per cent short after preferences.

Other senior Rudd government figures who can’t take anything for granted include Anthony Albanese in Grayndler and Tanya Plibersek in Sydney.