The island, once home to a Middle Saxon settlement, was found at Little Carlton near Louth, Lincolnshire, by archaeologists from the University of Sheffield after a discovery by a metal detectorist.
Graham Vickers came across a silver stylus, an ornate writing tool dating back to the 8th century, in a disturbed plough field. He reported his find and subsequently unearthed hundreds more artefacts, recording their placement with GPS, thus enabling archaeologists to build up a picture of the settlement below.
The artefacts include another 20 styli, about 300 dress pins and a huge number of sceattas – coins from the 7th-8th centuries – as well as a unusual small lead tablet bearing the female Anglo-Saxon name “Cudberg”.
Students from the university later found significant quantities of Middle Saxon pottery and butchered animal bone.
It is thought that the site is a previously unknown monastic or trading centre, but researchers are still at an early stage of their investigations.
Dr Hugh Willmott, from the university’s department of archaeology, said: “It’s clearly a very high-status Saxon site. It’s one of the most important sites of its kind in that part of the world. The quantity of finds that have come from the site is very unusual – it’s clearly not your everyday find.”
He said it resembled another Lincolnshire site, Flixborough, uncovered in the late 1980s/early 90s.
After the finds were reported, Willmott and doctoral student Pete Townend carried out targeted geophysical and magnetometry surveys along with 3D modelling to visualise the landscape on a large scale. The imagery showed that the island they had discovered was much more obvious than the land today, rising out of its lower surroundings.
To complete the picture, the researchers raised the water level digitally to bring it back up to its early medieval height, based on the topography and geophysical survey. “It [the site] is enclosed between a basin and a ditch,” Willmott said. “It was a focal point in the Lincolnshire area, connected to the outside world through water courses.”
Students from the university opened nine evaluation trenches at the site, which revealed a wealth of information about what life would have been like at the settlement. One area seems to have been for industrial working.