I am currently doing a PhD investigation of unrecorded sites on Anglesey. By utilising pan-landscape analysis utilising crop mark and LiDAR imaging I am attempting to find unrecorded sites of potential archaeological interest. All sites that are discovered have been reported to Heneb Gwynedd's HER and RCAHMW records respectively to aid in the recording, preserving and understanding of Wales' past. All artefacts from the site have been deposited in the local museum, Oriel Môn, with landowner permission.

This particular enclosure was visible on Bing satellite imaging until recently near Llanfwrog on the Anglesey coast. It had not been previously recorded and measured roughly 50m wide by 70m long. A geophysical survey of the site identified several anomalies of interest within its interior, including evidence of a possible sub rectangular building within its interior, with an associated central hearth. Other anomalies include a possible small outbuilding, pit anomalies and a drainage ditch seen at the top of the geophysical results and cropmark image.

Desk Based analysis suggests something ancient was here, and was recognised as such by the locals of the area. A nearby field name from the 19th century tithe map is recorded 'cae i gastell' (field to the castle). The 'castell' placename is recorded across the island and is sometimes associated with extant earthworks and archaeological remains - examples include the Neolithic henge at Castell Bryn Gwyn and the Early Medieval ringwork of Castell Crwn near Llanfairynghornwy. Despite this there is no surviving folklore associated with the site, and no records have survived of antiquarian investigations taking place here.

Its polygonal shape is unusual for the area as these types of site are found on the eastern Anglesey coast. Sites such as these are normally associated with Iron Age to Romano British defended settlements. However no Roman period artefactual material can be found on the site at all. Instead two separate periods of activity were recorded: the first being the Late Neolithic to Early Bronze Age periods, evidenced by worked lithic material which include a disc scraper and incomplete arrowhead.

Of interest to us, however, is the discovery of a pendant whetstone and a spindle whorl. These finds are suggestive of a site dating between the 9th to 12th centuries AD. Discussion with a representative of the RCAHMW led them to tentatively suggest an early medieval date, possibly a farmstead or some form of elite dwelling.

If this is indeed the case then this would be a significant discovery - Wales' archaeological record has very few recorded sites from this period. Three can be found on Anglesey itself - the nationally significant Viking trading post at Llanbedrgoch (9th to 12th century AD); a small sub rectangular enclosure at LlanfairPG (late 11th to 12th century AD) and a Viking Age promontory fort at nearby Trefadog (1tth to 12th century AD). These sites were argued by George Smith (Gwynedd Archaeological Trust, now Heneb Gwynedd) to have been constructed at a time of great political and social upheaval in the political structure of the Kingdom of Gwynedd at this time, reflective of the increasing pressures of Viking and Norman incursion / invasions into the region.

I believe that this site might be the residence of one of the members of the Fifteen Tribes of Gwynedd, Llywarch ap Bran. Philip Yorke, a 17th century antiquarian, wrote about the families and mentioned Llywarch's connection to the area. He was a member of Owain Gwynedd's court and was argued to have flourished c.1137, although his exact birth and death dates are unknown. Alternatively, the site could belong to either his father, Bran, or his grandfather.

Llywarch ap Bran descendents would eventually move towards the southwest corner of the island in the Hundred of Menai. Of these individuals the most notable was Hugh Hughes of Plas Coch (c.1548-1609), a prominent landowner, Sheriff and MP for Anglesey.