IT IS South Australia’s most enduring sporting rivalry, still rolling after 131 years.

The Port Adelaide Magpies and Norwood Redlegs were at it again on Friday night, at Coopers Stadium (Norwood Oval) in Adelaide’s cosmopolitan inner eastern suburbs.

Out that way every heart beats true for the red and the blue. Well, except for those wearing black and white. And there was no shortage of them on hand to cheer on their Magpies.

One was Lana Baker. She’s been a Port Adelaide member since 1965 but, unusually, has walked both sides of the fence.

"First I was a Norwood barracker, because I lived out here," she says. "I used to go for everybody who was playing against Port!

"Then I met my husband. He was born in Alberton and went to Alberton School. And if you were born down there you went for Port.

"Now I’m one-eyed Port Adelaide."

Mrs Baker’s son, David, played with the Williams kids "when they were little tiny boys". They grew up and played football together at Port. He’s now chairman of selectors at the Magpies.

The Port-Norwood game is the biggest of the year for the Bakers, barring finals, and Lana’s granddaughter, Jessie, has been coming every week since she was seven years old.

"Yes, it’s the biggest one," says Mrs Baker.

"It’s huge," adds Jessie, who – according to her grandmother, is "worse than me" when it comes to barracking.

So where does the Port-Norwood rivalry come from? And how has it endured the current day?

Time is one factor, but is not the sole ingredient. The clubs first met in 1878, but South Adelaide has been around just as long – and no-one hates them.

So what's with Port and Norwood supporters?

It’s geographic, cultural, tribal. It’s hereditary. It’s built on history, incidents, arrogance and jealousies. And mostly it’s about success. Who’s top dog.

Between them, Port and Norwood have won 63 of the 125 premierships on offer since the SANFL (then the SA Football Association) began in 1877.

Port was a foundation club of the league. Proudly working class, based around the wharves in Adelaide’s north-west. They’ve been at Alberton Oval for all bar two years since 1880, presenting an intimidating trip for visitors crossing the "cultural divide" past the Cheltenham cemetery down Port Road.

Norwood was established in 1878 and joined the league the same year. Based in Adelaide’s east – the wealthier side of town – Norwood supporters were, and are, proudly “red and blue-blooded”. The Redlegs have played at Norwood Oval on The Parade since 1901.

Norwood won six successive premierships from the year they entered the league, a sequence broken only by Port’s first flag in 1884. That early Norwood success was followed by more, with flags in 1887, 1888 and 1889.

The 1889 premiership win over Port is recognised as the first ever grand final in Australian football. Until then – and for some time after – clubs were awarded the premiership based on who headed the league after the home and away season.

But, at the conclusion of that season, Port and Norwood could not be separated. A play-off was required, which Norwood won 7.4 to 5.9.

By the turn of the century, Norwood had racked up 11 premierships to Port’s three and, in 1950, Norwood still led the premiership count 22-13.

And then came Foster Neil Williams.

Fos Williams took over as coach of Port Adelaide in 1950 and delivered a premiership in 1951. (He also delivered Mark, Anthony and Stephen Williams, who later played in a combined 10 premierships for the club, with Stephen coaching Port to three flags in the 1990s and Mark steering the AFL version to the podium in 2004).

The Magpies went on to win 10 premierships in the first 15 years of the Williams era, although Fos was not at the club for one of those – 1959.

Tough, brutal, uncompromising and feared became the Port Adelaide brand.

By 1965, Port passed Norwood in total premierships – 23 to 22 – and it stayed that way for a decade as Sturt became the SANFL's dominant force.

Norwood evened the premiership score under Bob Hammond in 1975, who would later become chairman of the Adelaide Crows. Port went ahead again in 1977, coached by John Cahill, breaking its own 12-year dry spell; Norwood duly levelled it in 1978.

Fast forward to a thriller won by Norwood in 1984 and the clubs had shared eight of the previous 10 flags – four each.

Great names peppered the game from both sides; legendary hard-man Garry McIntosh and the exquisite Michael Aish from the Redlegs, to four-time Magarey Medallist Russell Ebert, Craig Bradley, Greg Phillips and Bruce Abernethy at Port. There were many others.

The mid-1970s to late eighties saw great matches, great rivalries, bumper crowds and one common enemy – the Victorians.

South Australian football lost players to the VFL in increasing numbers; many of the named went, as did Kernahan, Motley, Naley, Platten – returning only for State of Origin.

In 1987 the West Coast Eagles and Brisbane Bears entered the VFL, leaving South Australia as the only mainland state without a team in the expanded competition. The SANFL resisted overtures to join, even mounting its own retention fund to keep its players at home.

Then, in 1990, it happened: the biggest act of treachery or the most overdue display of off-field initiative in the history of the SANFL, depending on which side of the fence you’re on.

Port Adelaide began negotiating with the now-AFL behind the other SANFL clubs’ backs to enter a team. When news of the dealing broke it was front page, back page and every other page. It split the state.

Bitter legal action followed, with Port stymied and the SANFL eventually entering a composite team – the Crows – for the 1991 season.

The 1990 grand final between Port and Glenelg – who led the legal action – was played with even more feeling than any previous. It ended in a Port win – its third in a row, and part of a string of nine in 12 years during the late eighties and nineties which took the Magpies' premierships count over Norwood out to 36-27.

During that time the knife in Norwood was twisted further. When a second AFL licence became available, Norwood mounted a bid in conjunction with Sturt. The AFL chose Port Adelaide, who entered the league in 1997.

AFL media manager Patrick Keane is a long-time Norwood man with a passionate view on Port's original bid.

"The AFL is a tremendous competition now, but put me back in 1990...," he said.

"That meant that my club Norwood, with an outstanding history of more than 120 years, lots of success, lots of great players, with a strong place in its state community, lost relevance. We don't have the status we once did, as one of the better of 10 proud clubs, because one club actively helped undermine our base.

"Nobody under 30 would understand it these days, but I had countless days watching Norwood play in front of crowds of 15,000, and sometimes 20,000, often against Port, but also against clubs like Sturt and Glenelg. I could also go out and stand right next to the guys who seemed bigger than life.

"Port helped kill that off, to ensure their club would prosper and consigned the other clubs who built a great competition to history."

So we come to the SANFL’s Rivalry Round.

Neither Port or Norwood have been in a grand final this decade – both have sat towards the bottom of the ladder for much of recent history – but it’s still the only local rivalry which regularly draws about 10,000 people through the SANFL gates.

They clash for the Gallagher Williams Perpetual Cup; the Williams moniker is well known while the Gallagher affiliation is a Norwood one.

Sam Gallagher played for Norwood in the fifties, while his son Phil was also a premiership player in the seventies and eighties. Both named in Norwood’s Team of the Century, Phil’s son James is Norwood’s current captain.

Yes, it’s a rivalry that’s geographic, cultural, tribal, hereditary.

And on Friday night it was James who held the cup, with the Redlegs leading all night to beat the Magpies by 22 points – 12.17 (89) to 10.7 (67).

Trust it will be on again in round 18 and Lana and Jessie will be there, hoping for a different result.

The author doesn't barrack for Port or Norwood. Two of his favourite football days remain the 1983 second semi-final when West Adelaide hammered Norwood and the 1991 elimination final when the Bloods handed Port their biggest ever finals loss.

The views in this story are those of the author and not necessarily those of the clubs or the AFL.