The remains of one of the oldest churches in Britain have been excavated for the first time in more than 100 years.

The sixth-century St Piran's Oratory near Perranporth in Corwall was first discovered at the end of the 18th century. It was the subject of two archaeological excavations in 1835 and 1843 before being encased in a large concrete structure in 1910 to preserve the fragile ruins. A number of skeletons, including one of a large headless man and a woman with a child in her arms, were found at the site.

The structure was removed in 1980 and the site was buried in sand because of continuing problems with vandalism.

Now a team of 90 volunteers under the auspices of the St Piran's Trust has dug out the site by hand.

Ian Saltern, company secretary for St Piran's Trust, told the BBC: "It's in a better state than we could have hoped for. The preservation is pretty good for a building that is more than 1,000 years old."

Open days for the public will be held on 22 and 23 November.

St Piran is the patron saint of tin miners and his flag, a black cross on a white background, is the emblem of Cornwall. He is said to have come from Ireland, where he was lashed to a millstone by heathens and pushed over a cliff; however, he floated across the Irish Sea to Cornwall, where he became an abbot at Perranzabuloe. He was a great preacher and his first disciples were a badger, a fox and a bear.

The story of St Piran is retold in a drama on the dunes near the oratory on the Sunday nearest to 5 March, St Piran's Day, which is widely celebrated across the county.