When an archaeology student lost his footing on an excavation site in Shetland, he had no idea he was standing on a house which had been buried for 2,000 years.

But now Bradford University archaeologists have had their first glimpse of the Iron Age building and are looking forward to stumbling upon more.

The complete, drystone house at Old Scatness was discovered after the student, a member of the excavation team from Bradford University and Shetland Amenity Trust, put his foot through a hole in the building's roof.

County archaeologist Val Turner said he was lucky not to break his leg.

She said: "The stones were quite unstable as there was nothing underneath.

"Shetland has some wonderful archaeological sites and we knew that this site was very rich in archaeology, but this has surpassed our wildest expectations. As far as I'm aware, this is unique."

The well-preserved house is part of a village settlement surrounding a broch-an Iron Age tower found throughout the north and west of Scotland. Features of the structure include cupboards built into its walls and decoration with bright yellow clay.

Bradford University's partnership with the trust stretches back to 1995 when its geophysics team was invited to survey the site.

Students and staff were chosen to help on the dig because of their advanced scientific techniques such as luminescence dating - measuring exposure to light in soil.

Bradford University lecturer and director of the excavation Steve Dockrill said: "This is an amazing building. Excavation this summer has revealed what we think are the roofs of several other similarly complete buildings still to be excavated within the settlement.

"The building seems to have been deliberately in-filled from a hole in the roof and then sealed."

Finds inside include a whalebone weaving comb and a large number of animal bones, including those of a horse.

Archaeologists have also discovered metal workings on the site which they now believe to have been a major industry on the island.

Miss Turner said: "Shetland is a bit of a windy place and not hospitable for agriculture, so we're beginning to think that it was the mineral resources such as copper which were important. It's a key site."

The dig has attracted historians and visitors from as far afield as America and the trust is hoping to continue excavation subject to further funding.