Royal Commission aerial reconaissance on 10th Dec 2012 (AP_2012_5144) highlighted a distinctive pattern of field boundaries close to Ymwlch which seem to fossilise a concentric oval enclosure on a large scale. This enclosure appears to be aligned on the early church at St Tanwg's, Llandanwg (NPRN 43901) and the present field boundaries may infact fossilise a prehistoric or early medieval ecclesiastical enclosure or cemetery related to the early church site.

The potential enclosure indicated by the distinctive field boundaries suggests a central oval enclosure measuring 105m x 57m, set within a wider outer concentric oval enclosure measuring 520m x 260m. The present trackway to Ymwlch, which takes a course along one of the enclosure cross-boundaries aligned on the coastal setting of St Tanwgs, may reflect an earlier path through the site.

If the potential enclosure is ancient, there may be archaeological deposits associated with the extant boundaries or the central enclosure.

T. Driver, RCAHMW, 2014