For a city of 400,000 people, Canberra residents are good at turning up to things. It could be the country’s most popular flower festival, or its loudest muscle car jamboree or a game of AFL in the snow; this town will generally provide a crowd.

Still, a common tone often accompanies these events. For all their reliability, Canberra crowds can tend towards the genteel (well, maybe not Summernats). People sensibly plan ahead, packing sandwiches and flasks of coffee; they bring picnic rugs and remember their wide brim hats on a sunny day. Arguably more than any other Australian city, Canberra crowds are happy to clap opposition players with a fair-minded politeness.

Last week’s NRL preliminary final between the Canberra Raiders and South Sydney Rabbitohs was nothing like that. From the opening Viking Clap to Josh Papalii’s late surging try, there was something manic in the air. One way of describing it would be passionate; another would be mildly unhinged.

For Raiders fans, this hunger was well earned. Since the team’s remarkable run of success in the late 1980s and early 1990s, ending with their last premiership in 1994, it has been a lean quarter century for the Green Machine. Apart from a few encouraging finals spurts here and there, the club has not really looked close since the glory days. In fact, with the exception of the consistently victorious Canberra Capitals basketball team, a Brumbies Super Rugby title in 2004 and a couple of semi-professional baseball and ice hockey championships, recent Canberra sporting success has been largely defined by honourable losses (the jury is still out on whether Greater Western Sydney constitutes an ACT team; after Saturday, perhaps not).

Raiders fans cheer as the Raiders’ Viking horn passes by. Photograph: Lukas Coch/AAP

For now, rare September success has brought to town the wonderful, ritualistic kitsch of grand final preparation. It has been a week of dyed green sausages, vintage Canberra Milk jerseys and newspaper front pages with happy fans jumping up and down in empty fields. On Wednesday, hundreds of people lined the streets at Raiders headquarters to watch the players leave for Sydney on a Murrays bus. At the front of the convoy was the giant Viking horn, strapped to the back of a truck and ready to head down the Hume Highway.

More moving has been the outpouring of genuine emotion from fans since Friday night’s win. Some of these stories come from people who have followed the team since the beginning, enduring decades of brutal winter nights at Bruce Stadium. One of these was Tony Wood, the man beneath the Victor the Viking mascot suit since 1983. Wood was so excited by the victory that, after the siren, he threw off his headwear in jubilation. It was only the second time he had unmasked himself in 37 years.

Other reflections reveal something distinct about life and culture in the ACT. More than most other towns in Australia, Canberra can be a transient place: people often come for work or study, leave and then come back. They arrive with loyalties, which the city slowly chips away.

One blog post this week compared the experience to the Ship of Theseus – the mythical boat that, over many years, replaces every original piece of wood until something distinct stands in its place. Initially a Brisbane supporter, the author found that “each [Raiders] game, each memory [became] a plank of wood in the ship that is your fandom for your favourite team … I’ve felt the rotting wood of many of my old Broncos memories get replaced by sturdy new Raiders ones.”

In Canberra, new affections slowly seep into your skin, like the blue algae in Lake Burley Griffin.

Grand final week lends itself to myth making, however grandiose or silly, and two different stories could be told about this team – each mirroring the city itself. One is about a scrappy unit, built on defence and savvy recruiting; a lucky improvisation by determined underdogs. In Paul Daley’s history of the capital, Canberra, the journalist and writer described the town as an “accidental miracle” – a planned city that resisted its design from the start. This would be fitting in its way.

Raiders hero Josh Papalii acknowledges fans during a training session during the week. Photograph: Mark Evans/Getty Images

The alternative story speaks to growth and maturity. Canberra is an expanding city, forecast to reach half a million people within a decade (last election, it gained a third seat in the federal House of Representatives). It just finished the first stages of a tramline that will eventually connect every corner of the city; the same year it officially generated 100% of its energy through renewables. It is a place with more things to do and people to see than ever before. In February, it hosted its first cricket Test match. All in all, it is a town ready to shed its reputation for, in Daley’s words, “tetchy defensiveness bordering on paranoia”.

In the same way, the Raiders’ victory on Friday night was no ragged fluke; it took more than guts to hold together amidst relentless goal line assaults. No, this was built on a quiet confidence and professionalism, as befits a city finally growing into itself.

It is also the exact kind of organised self-possession that wins grand finals. For Raiders fans new and old – for the Territory itself – all that matters is that it lasts 80 more minutes on Sunday night.