A grandfather has unearthed an 11th-century abbey in his back garden.

Peter Laurie, 73, and his grandson Oscar, 16, were searching for the remains of a Roman road when they came across their unexpected treasure.

Peter Laurie is a retired journalist and keen amateur archaeologist and his main interest is Roman campaign roads.

He said: “From what I knew of the history of this area, I thought it was possible there could be a Roman road running through my garden.”

To test his theory he started digging with his grandson Oscar.

They dug six feet down and unearthed a wall at his Abbotsbury home.

Peter Woodward, of Dorset County Museum, believes it to be a hitherto unknown outbuilding of the former Benedictine abbey that stood in the village.

After a few days of excavations with friends they discovered a substantial freestone wall about one metre thick and one metre high that once enclosed several levels of farm buildings. The lowest, about six feet deep, with fragments of clay pipe stems, dates back to Shakespearean times.

Evidence also indicates that one of the buildings burned down: pieces of scorched wood and large nails that could have come from roof trusses have been found in the pit.

It was first time lucky because he had never undertaken a dig before.

“I never suspected there was all this different life right here under my lawn,” said Peter, who has lived there for 15 years.

The abbey at Abbotsbury was founded in the 11th century and dissolved during the reign of Henry VIII. The buildings were then demolished so the stone could be reused.

Mr Laurie’s house used to be called Home Farm and in the nearby barn the date of 1747 is carved on the wall.

“I suspect that was when the farm was reorganised and the house enlarged.

“My feeling is that the old buildings – including those in the pit – had been knocked down a long time before then. The Estate Map of 1758 shows nothing on the dig site,” he said.

He plans to resume digging in the next few months when his colleague from the Dorset Roman Roads group, John Surowiec, returns from a trip to Poland.

“We’ve had to dig up six feet of silt to go back 500 years,” he said. “At that rate we will have to go down 24 feet to try and find a Roman road.”

Mr Laurie will give a talk entitled Tracing Roman Roads In West Dorset at the Bridport & District U3A meeting on June 22 at the Christian Fellowship Hall, Bridport, at 2pm.