Record-breaking haul from Gaul discovered at farm in Brittany

Asterix and Obelix, had they existed, might have paid for their mead and other magic potions with gold-silver-copper coins stamped with elaborate images of men and horses.

The largest treasure trove of pre-Roman, Gaulish money ever to be found has been discovered in central Brittany.

The 545 coins each worth thousands of euros to collectors but priceless to historians and archaeologists could overturn much of the received wisdom about the complexity, and wealth, of pre-Roman Celtic society in France. Why was such enormous wealth, a king's ransom at the time, buried in the grounds of a large Gaulish farm 40 miles south of Saint-Brieuc in the first century BC? Why was the hoard never recovered?

"Treasure on this scale would only have been used for transactions between aristocratic families," said Yves Menez, an archaeologist specialising in iron-age Brittany. It has always been assumed that the Celtic nobility lived in fortified towns, not in the wild and dangerous countryside. "The reality must have been more complex," Mr Menez said. Like all Gaulish coins, the 58 "stateres" and 487 quarter "stateres" found near to the village of Laniscat are copies of early Greek money.

Gauls served as mercenaries in the armies of Alexander the Great. The money that they brought home served as the model for home-minted coins. Some of the new treasure trove, rescued from the site of a proposed dual-carriageway, have the familiar Celtic monetary pattern of a horse on one side and a man's head on the reverse. Other coins have hitherto unknown designs, such as horses with human heads.

There are also images of riders and wild boars.

Smaller caches of Gaulish coins have turned up in the past but rarely of such quality and never in such numbers.

Most transactions for goods in Gaulish times were conducted through barter.

Coins were for the super-rich. "This is an exceptional discovery," said Mr Menez. "It represents a colossal fortune for the period. Each of these coins was like a 500 euro note today."

The hoard of coins was discovered by the French government agency, the Institut National de Recherches Archologiques Prventives (INRAP), which has the right to explore any potentially significant site before a road or new building covers it forever. The coins are believed to have been minted in around 75 to 5BC. They were probably buried just before, or during, the first Roman invasions of what is now northern and western France.

A dig led by INRAP archaeologist Eddie Roy discovered the coins scattered over 200 square metres of a site soon to be occupied by a new by-pass.

It is believed that they were all buried together but disturbed over the centuries by agricultural ploughing. "We found a single coin about 30cms down and then we started a systematic search," Mr Roy said.

"We found 50 more in a single day and then, with the help of metal detectors, we located all the others."

The dig unearthed the remains of a large manor house or farm, which is thought to have belonged to the "Osisme" people a Celtic tribe living in the far west of the Breton peninsula. The coins were probably buried in the farm's boundary embankment. Why? To hide the wealth from the Romans? Possibly. The farm was occupied for several centuries after the treasure was buried but the coins were never recovered: one small part of Gaul which resisted the Roman invasion.