Senua - probably an older Celtic goddess, who was then adopted and Romanised. Photo: British Museum

She is faceless and armless, but she has a name: Senua. A previously unknown Romano-British goddess has been resurrected at the British Museum, patiently prised from soil-encrusted clumps of gold and corroded silver which have buried her identity for more than 1,600 years. Her name is published for the first time today.

The 26 pieces of gold and silver, found in a Hertfordshire field last year, are believed to be the treasures of a shrine in her honour, carefully hidden as some disaster loomed in the late 3rd century. The fact that they were never recovered suggests the protection of the goddess did nothing to save her conscientious devotee.

"This is a hugely significant find, of national and international importance," Ralph Jackson, Roman curator at the British Museum, said. "Personal hoards, hidden in some crisis, are reasonably common. To find a hoard of a temple treasure, such as this one, is incredibly rare, not just in Britain but anywhere. To give Britain a new goddess is extraordinary."

He believes Senua was probably an older Celtic goddess, worshipped at a spring on the site, who was then adopted and Romanised - twinned with their goddess Minerva - by the invaders. There is a direct parallel at Bath, where the Romans seamlessly absorbed the Celtic god Sulis, and a much older shrine, into their religion.

Senua's shrine may have been a ritual spring, into which offerings were thrown, surrounded by a complex of buildings including workshops and accommodation for pilgrims.

It was certainly no humble crossroads shrine. The offerings include silver plaques with gold highlights, seven gold plaques and a superb set of jewellery, including a brooch and cloak clasps. The plaques still have the metal tabs which allowed them to be set upright, and are so thin that they would then have shivered and glittered in any draught.

Mr Jackson spent months poring over the faint inscriptions on the votive plaques, some incised, some punched out in tiny holes. He could make out some of the names of the donors, including Cariata, Celsus, Firmanus and Lucilia, and one complete inscription recording that Servandus from Spain was well pleased with the favours the goddess had done him, and was paying her back: "Servandus Hispani willingly fulfilled his vow to the goddess".

The jewellery incorporated older gems and glass beads, including a superb carved cameo of a lion trampling an ox skull - a classical allegory of all conquering death - which was already old and worn before it was set into the brooch. All of the jewellery shared intricate decoration in minutely coiled wire, and the set may have been specially made as an offering.

But who was the obliging goddess? Several of the plaques showed a classic image of Minerva, with spear, shield and owl but Dr Jackson could not make the letters spell her name. Only when the plaques were x-rayed did he realise that he was looking at the name of a wholly unknown goddess.

"It was an extraordinary moment," he said, "Like seeing her reborn before my eyes."

The hoard comes from a unique find a year ago by an amateur using a metal detector, in a field near Baldock in Hertfordshire. Though other scraps of ancient metal had been found, there was nothing to suggest the site was of major significance. It was immediately recognised as legally treasure, which must be reported. Local and British Museum archaeologists joined the search. The finder and the landowner shared the £35,000 reward, which the British Museum paid with grants from their friends group and the Art Fund charity.

When the field was excavated the broken-off base of the small silver statuette was found, and it identified the figure as Senua. She remains teasingly elusive. Only the back view, of a graceful woman with hair coiled in a bun, remains intact. The breast, arms and face of the goddess rotted away in the soil centuries ago. Much work remains to be done on the finds and at the site. A bundle of gold plaques remains clumped together with mud, like trampled autumn leaves.

The field may still hold bronze plaques, not considered valuable enough to hide, and it may even eventually yield some clue as to the catastrophe which overwhelmed Senua's shrine, and the faithful guardian of her treasures.