Experts and volunteers working at Castilly Henge have been trying determine if it is the county’s lost great stone circle

It was a grey Cornish autumn day, but Henry Stevens’s tough shift digging in a field next to the A30 was about to get very exciting.

Her eye was caught by something glinting in the soil and she picked up a flake of flint that had lain for thousands of years within what might just turn out to be a Cornish version of Stonehenge.

“I screamed,” said Stevens, 27, a volunteer on the Castilly Henge archaeological dig. “I was so excited. I held it up to the sky and the light shone through it. Lovely.”

The flake was probably the byproduct of a Neolithic person fashioning some sort of tool. “As I work here now, I think about the people who were here before us,” said Stevens. “Why did they build this? What drew them here?