Full description from: Driver, T, Pembrokeshire: Historic Landscapes from the Air, RCAHMW, pages 162-3.

'During the dry summer of 1990, barely 500 metres from Haverfordwest airport, a very rare type of prehistoric ritual monument was discovered by Chris Musson, then of the Royal Commission. Perfect seasonal conditions for cropmark formation, combined with perfect evening summer sunshine striking low across a ripened arable crop, combined to reveal the position of about thirty pits in a perfect circle. This cropmark represents the buried remains of a prehistoric circular temple, long since erased as a standing monument. The cropmarks, which have not been excavated, appear to show the site of a timber circle, a particular type of later Neolithic or early Bronze Age ritual monument comprising a circle of upright timbers, most commonly built around 3,000 BC. A complex late Neolithic timber circle was excavated near Welshpool in 1990-2 at Sarn y Bryn Caled, and its subsequent reconstruction gives us some idea of how impressive the Withybush monument may have appeared to the rest of prehistoric Pembrokeshire. Alternatively, the cropmarks may represent a Bronze Age pit circle, where, instead of standing timbers, the holes would have contained special offerings and perhaps cremated remains, or even a stone circle whose stones have been removed. Without excavation its interpretation as a timber circle is the most likely, and as such its discovery reminds us of what else may be awaiting discovery in Pembrokeshire. The chances of similar monuments existing elsewhere are high, but if they lie under woodland, under towns, or in damper ground where cropmarks never form it is unlikely we will ever rediscover them. We can only say with some certainty that the present-day distribution of Bronze Age burial cairns and stone circles on the hill tops and upland fringes of Pembrokeshire is not representative of the original distribution of prehistoric temples. While the Gors Fawr stone circle sits in splendid, rugged isolation at the foot of the Preseli Mountains, it is entirely plausible that similar monuments, now lost or ploughed away, once dotted the productive Pembrokeshire lowlands or overlooked the wide vistas of the Daugleddau estuary.

(caption for illustration) Withybush circle, near Haverfordwest. Cropmarks of about thirty pits, highlighted by the setting summer sun, show us the original location of what may have been an impressive late Neolithic timber circle. Such a monument may have contained special burials at its centre and a designated gateway somewhere on the perimeter for onlookers to enter and observe or take part in rituals. This circle of pits was scheduled as an ancient monument of national importance on the basis of the aerial evidence alone (RCAHMW, 90-cs-0616).'

T. Driver, 21 June 2007