Llangibby Castle (Tregrug)

Llangibby Castle, often called Tregrug, occupies a wooded ridge near the village of Llangybi in Monmouthshire, Wales. A Norman motte-and-bailey on the site is first recorded in 1262, though by the mid-13th century the estate had already passed into the de Clare family and was held for some years by Bogo de Clare. In the early 14th century work began on a new stone-enclosed residence, probably initiated by Gilbert de Clare; later ownership briefly passed to the Despenser family and Hugh Despenser is associated with the late medieval building whose ruins largely survive.

The site was attacked during the revolt of Llywelyn Bren in 1316. After Gilbert de Clare’s death in 1314 later building and maintenance may have been undertaken by his widow Matilda and by his heiress Elizabeth de Burgh. The surrounding community suffered a severe outbreak of plague in 1369, and by the 16th century the castle had fallen into disuse. The estate became Crown property and was sold by Queen Mary to the Williams family of Usk in 1554.

During the English Civil War the derelict site was refortified and held by Sir Trevor Williams, 1st Baronet; the castle was deliberately slighted at the war’s end. In the later 17th century the Williams family built a new house nearby, usually referred to as New Llangibby Castle, remodelled parts of the older ruin as a landscape-garden feature and around 1707 planted an avenue of Scots pines down to the River Usk. New Llangibby Castle was demolished in 1951.

In the late 19th century the earlier motte was planted with conifers and rhododendron after a period of use as a bowling green; those plantings were cleared in the early 21st century. A 2010 archaeological investigation concluded that the banks and ditches around the stone enclosure were largely reworked during the Civil War, that the site was substantially remodelled in the later 17th century to create a new principal entrance and a landscaped interior, and that contemporary accounts record expenditure on elaborate gardening. Investigators described the principal structure as primarily residential in character, functioning as a medieval pleasance. The north and south stable ranges that date to the later house survive and are statutorily protected, and the castle with the remains of the motte-and-bailey is scheduled for preservation.