Sheepfolds dot the grass between the church and Death Alley, the concrete strip where bareback showmen race

Go east for a woman, go west for a horse. No trophies for guessing which part of that old adage still holds true. Each autumn, horse-mad Ireland packs its saddlebags and canters westwards to Ballinasloe in County Galway. This is the site of the Great October Fair, one of the oldestand liveliest horse-fairs in Europe.

The sheer diversity of horseflesh on display is bewildering - a snorting, stomping kaleidoscope that spins from elegant mahogany hunters to native Connemaras wearing shaggy winter coats. Half-breds, a cross between an Irish Drought mare and a blood stallion, prove their worth as potential showjumpers in a lunging ring.

One section of the Green brims with piebalds; burly black-and-white Cobs destined to pull a city scrap cart, and smaller ponies or "trotters", skilled in harness racing. Most trading in "coloured horses" takes place between the country's nomadic travellers, tinkers and gypsies.

This being an Irish horse fair, goats, rabbits and lurcher pups are also on sale. Sheepfolds dot the grass between St Michael's Church and Death Alley, the concrete strip where bareback showmen race along at breakneck speeds. Blot out the burger vans and what's left is a place that time and the agricultural revolution forgot.

Numbering only 6,000 inhabitants, Ballinasloe is the last of the great country fairs that once flourished throughout Ireland. Today's farmers auction their livestock in clean but soulless marts. Like the wandering ballad singers, the cattle drovers, with their herds of Connaught Longhorns, are gone now. Ballinasloe is a gathering for Ireland's throngs of amateur horse breeders and their raggle taggle camp followers. Braving cold and damp, the same characters turn up every year: the wheelers, dealers and three-card tricksters; the taxidermist and the travelling farrier; the Holy Joes, fortune-tellers and the man selling copies of Old Moore's Almanack with its smudgy pages of racing tips and weather predictions.

Stocky men in cloth caps, faces ruddy as Armagh apples, still mouth the same peculiar jargon as did their grandfathers. Neither Irish nor English, a horse-trader's language is an incomprehensible exchange of nods, winks, spits and handshakes.

Many buyers return year after year, dreaming of spotting the bargain that will prove to be a champion worth thousands. It's not impossible. Tom, a farmer from Mayo, told me of Leapy Lad, bought for a song on the Fair Green. The horse went on to win major showjumping trophies before being sold in America for $250,000.

Those who do come across some cut-price Arkle can expect the deal to be struck in the time-honoured way. No cheques, no credit cards, no promises.

After some flurried haggling, maybe a price will be agreed. Palms are then oiled with spit before a slapped handshake cements the deal. Finally, after wads of grubby bank- notes are exchanged, comes the vital part of proceedings - the passing of the luck money from seller to buyer. Usually around IR pounds 20 nowadays, luck money is returned to bring the new owner good fortune.

And some of them will need it. With no rules, regulations or forms to fill in, anyone can sell horses here. Tales of stolen ponies and villainy abound. That frisky filly could well be a tired old nag, pepped up for the day by a ginger suppository. Buy her and all you'll have as recompense is a hard luck story to tell.

Onlookers also need their wits about them if they don't wish to get trampled underfoot. Then there are the pickpockets and the pedlars, all bent on maintaining the age-old tradition of parting fairgoers from their money.

Though its official fair charter dates only from 1722, Ballinasloe has been pulling in punters since Celtic times. The town's Irish name, Beal atha na Sluaighe, translates as "ford of the hostings", the hostings being the armies of the Chiefs of Connaught who crossed the River Suck here on their journeys to pay tribute at Tara.

When you're ankle-deep in nasty smelling substances, it's hard to believe that the days of equine supremacy are over. But of the 4,000 horses offered for sale during Fair Week, few are real working beasts any more.

Leaving part of Fair Week free for parades, dog shows, showjumping and drinking sessions, Sunday, Monday and the final Saturday are the days for serious horse trading. The days for serious bible-thumping, too.

"Are you saved?" bellowed a crazed individual last year as I paused to listen to the honeyed patter of a three-card trickster. Wielding a John 3:7 placard, dressed entirely in black, this wild-eyed messenger began an unbridled rant about being born again. Leaving him to it, I fled up a flight of slippery steps to Dunlo St and the sanctuary of the Jekyll & Hyde Bar.

Air heavy with tobacco smoke and horsey conversation. Pints of sinful- looking stout lined up in regiments along the bar. No doubt John 3:7 would disagree, but this seemed the perfect place to hold my own sort of revival meeting.

Next week: an Independent travel special report on Ireland

When to go

This year's Great October Fair runs from Sunday 1 October to Saturday 7 October. (Most of the horse-trading takes place on Sunday, Monday and the final Saturday).

How to get there

Flights from many British airports to Dublin cost around pounds 60 return, through Aer Lingus (0181-899 4747)

or Ryanair (0171-435 7101). From the Irish capital, Bus Eireann (00 353 1 836 6111) has eight buses a day to Ballinasloe, price pounds 14 return.

Who to ask

Irish Tourist Board, 150 New Bond St (though the entrance is in Bruton St), London W1Y 0AQ (0171-493 3201).