The graffiti was discovered by staff on Tuesday

Staff at Skara Brae arrived on Tuesday to find graffiti scribbled on the walls of the 5,000 year-old village.

Police are keen to trace a group of visitors who are believed to have been travelling in a silver Hyundai.

The site attracts thousands of visitors every year and is one of Orkney's most iconic tourist attractions.

Mary Dunnett, monument manager of the site which is looked after by Historic Scotland, said that the graffiti was one of the first things that visitors to the village would see.

I'd imagine it will cost a lot of money to remove this without damaging the stone too much

Mary Dunnett

Historic Scotland

"Someone has come in and gone into house one, which is one of the best houses here in Skara Brae," she said.

"They've put marker pen on a dresser and they've also written their name, put a smiley face and the date on one of the bedposts so it's quite prominent.

"I'd imagine it will cost a lot of money to remove this without damaging the stone too much."

Sergeant Gregor Hay, who is leading the investigation, said that they had identified the suspect as a tourist due to travel back to the mainland by ferry on Friday.

"We believe the suspect has been stupid enough to use his own name," he added. "We are keen to speak to a family who are still on the island."

Gradual excavations

Skara Brae was first discovered following a major storm in 1850, which battered the island to such an extent that an outline of a series of stone buildings were revealed.

A series of excavations were carried out over the next century, finally revealing eight stone dwellings that were originally believed to be an Iron Age settlement.

However in the 1970s radiocarbon dating showed that the village was originally built between 3200 and 2200 BC.

Today the ancient village is under serious erosion threat from the sea and Orkney's fierce weather conditions.