WHAT you first notice going into Ballaghderreen is that, there's something about the banners. The legends aren't the usual cheerful banalities laced with a laboured local pun. "You are entering Free Mayo," says one. "Mayo's last line of defence," says another.

Something else that can be noticed by a driver coming into town from the Charlestown side is that if you set the mileometer at the right moment, it will indicate that you're four and a half miles past the `Welcome to Roscommon' sign by the time you reach Ballaghderreen.

The anomaly is well known. The town which sent off Sean Flanagan to captain Mayo to their last two All Ireland successes, in 1950 and 51, is actually in Roscommon for local government purposes. Only in the GAA's atlas is it part of Mayo.

The "last line of defence" is a deft reference to Flanagan's son Dermot and Kevin Cahill, two `Ballagh' men who comprise two thirds of Mayo's full back line tomorrow.

What's less well known is that the frontier town rivalry sometimes takes more heated and abrasive forms. Recent years have seen a stronger undercurrent of resentment creep into some Roscommon attitudes towards this Mayo outpost.

Most people prefer not to talk about the differences of opinion that in heated circumstances have led to representations at Connacht Council and Central Council level seeking the annexation of the town into Roscommon.

The precise history of the matter is unclear. Around 1915, the town passed from Mayo to Roscommon. There are competing explanations as to how this happened. According to one, it was because the Mayo local authority owed money to Roscommon's and the debt was discharged by banding over the town and its rates paying inhabitants.

This is history from a Mayo perspective: the town sold into bondage because of Roscommon avarice.

Alternatively, you can have the scenario that a local MP, unhappy at the more expensive rates in Mayo, arranged for the boundary to be redrawn. It had beep at the Lung river (on the Dublin side) but was changed to four miles the other side, the road to Castlebar.

Roscommon subtext: the town was happy to trade its Mayo status for cheaper rates.

Faugh a Ballagh was the original club playing in Mayo and it changed to Roscommon for about a year. Again, local accounts differ.

Roscommon historians say there was no particular reason for the switchback whereas Mayo partisans say the club was thrown out of Roscommon because it won so many trophies in its one year there.

Time passed and the arrangement didn't seem to bother people. It had unusual side effects. There are many in the town who are loyal to Roscommon in both a municipal and a football sense. If, however, they have been born in Ballaghaderreen they have no choice but to play for Mayo should their game be up to intercounty standard.

Consequently, some Roscommon supporters have ended up playing intercounty football in the green and red of Mayo. The All Ireland was brought to the town in the early 1950s and although a failed attempt to review the situation at Central "Council was raised in the following decade, life was quiet enough.

Everyone agrees that it was the 1989 All Ireland between Mayo and Cork that got the pot boiling. To what precise extent people disagree. There is a natural tendency to play down the divisions in the town but Ballaghaderreen became a focal point for Mayo hype.

The team's manager of that time, John O'Mahony, is from the town and so are two of the team that started that match seven years ago, Dermot Flanagan and Noel Durkin.

Some supporters painted the road red and green and together with other flights of enthusiasm, caused Roscommon sympathisers to take umbrage. Adding to the delicate situation was the fact that Mayo had beaten Roscommon after a replay in that year's Connacht final.

Cross community relations rigidified and the county's first All Ireland final in 38 years became a source of friction rather than bonding. Attempts were ultimately made to form a new club, St John's, and affiliate it to Roscommon.

Durkin's pub in the Square is considered the town's Mayo capital. Inside it last Thursday, a video of the semi final win over Kerry was playing to an unflaggingly rapt audience of two or three.

"Looks like we're going to win this one," says one viewer, cheerily gesturing at the screen. In a quiet corner Joe Dillon, chairman of the club, plays down any tensions this time around.

Around the corner, as his shop is being re decorated, Mattie Towey - the Godfather of the Mayo connection - sets out his stall. He is a long, long serving member of the association. He won a junior county title with the club in 1941, just six years after Mayo won their first All Ireland. His formulation is simple.

"We pay rates in Roscommon and play football in Mayo. In the last 20 years there's been a bit of trouble. The oul' stock, like me, are all Mayo and the young ones are Roscommon. They've brought it on two occasions to the Connacht Council and once to Central Council.

"Last Saturday fortnight they came in from Frenchpark wearing Meath jerseys. In 89 they were doing the same thing, shouting `Up Cork, Up Cork'." He remains concerned about the future. "I maintain when the oul stock is dead in this town, they'll change the club and bring it into Roscommon." A couple of doors from Durkin's is the Arch Bar, seat of councillor Tom McGarry.

Requests to have a word with him about the match evoke the response: "You'll only get him into trouble." "He'd be more outspoken on the Roscommon side," says McGarry's son Declan carefully. "He never played much football but she's quite witty about it." Preferring not to unleash his father's wit on Mayo with an All Ireland final in the offing, Declan - a Ballaghaderreen senior player - puts the Roscommon side.

"Sometimes you get a situation coming up to a Roscommon Mayo match, a few lads get a bit of porter taken but there's no animosity. The whole club is behind the team on Sunday. There's a lot of allegiance to Kevin Cahill (Mayo's full back).

McGarry believes that players in the town should be allowed opt to represent Roscommon, although the current position was upheld by Connacht Council when the St John's club failed to secure authorisation in April 1990.

"If the clubs in Roscommon were as organised as Ballaghdereen, things would be better for the county, says McGarry. "The majority of the club are Mayo people and it's a credit to them. But I'd say this, if we were playing in Roscommon we'd have more county titles." And maybe Roscommon would have one or two more All Irelands.