Coity Castle

The castle began as a late 11th century ringwork. A rectangular stone keep and the main curtain wall were added by the Normans in the 12th century, under the de Turberville family. The three-storey keep was primarily a defensive structure.

Extensive reworking took place in the 14th century, when a domestic range was attached to the keep by the middle gatehouse. New stone vaults replaced the earlier timber floors. The central octagonal pier for the vaults is still prominent among the castle ruins. An adjoining chapel wing with a tall east window was added to the first floor at the eastern end of the domestic range in the 15th century.

During the 16th century Coity Castle, by then owned by the Gamage family, underwent a complete remodelling of the living quarters, including the addition of a storey, new windows and two chimney stacks. The principal chambers lay on the upper floors. The range of domestic apartments comprised a central first-floor hall set above a vaulted undercroft, from which it was reached by a grand spiral stair. To the west were ground-floor service rooms, probably including a kitchen, with ovens. The base of a ruined large malting kiln remains. On the far side of the range, a tower projecting from the curtain wall contained latrines. The second floor housed private apartments.

Turberville

The de Turberville family held the Lordship of Coity from c. 1092 to 1360, which had been founded by Sir Payn de Turberville, one of the legendary Twelve Knights of Glamorgan of Robert FitzHamon, 1st. Lord of Glamorgan. Richard de Turberville, seemingly his 6th great grandson, died in 1384 without male heir, leaving his four sisters as co-heiresses:

• Katherine de Turberville, the eldest, had married Sir Roger Berkerolles (d.1351), another descendant of one of the Twelve Knights of Glamorgan, of East Orchard, St Athan. The tomb effigies of Katherine and Sir Roger can be seen in St Athan's Church. Their son was Sir Lawrence Berkerolles (d.1411), the last of the Berkerolles, who died without progeny.
• Margaret de Turberville, the second daughter, married Sir Richard Stackpole, whose daughter Joan Stackpole married Sir Richard Verney.
• Agnes de Turberville, the third daughter, married Sir John de la Bere of Weobly Castle, Gower.
• Sarah de Turberville, the fourth and youngest, married William Gamage of Rogiet.

Berkerolles

It was Sir Lawrence Berkerolles (d.1411), son of Katherine the eldest daughter, who succeeded to Coity. His sister Wenllian Berkerolles had married Sir Edward Stradling of nearby St. Donat's Castle. Under his tenure Coity Castle resisted an attack by the forces of Owain Glyndŵr (Owen Glendower) and a long siege followed lasting into 1405. King Henry IV was petitioned by Parliament to send a relief force and he dispatched three Bristol sea captains to resupply the besieged garrison. The Berkerolles' tenure of Coiety ended on October 18, 1411, on the death of Sir Lawrence sine prole.

De la Bere

The heir of Sir Lawrence Berkerolles was his 1st. cousin once removed, the minor Thomas de la Bere, the son of John de la Bere deceased, son of Agnes Turberville (3rd. sister of Richard) and Sir John de la Bere. Margaret de Turberville the 2nd. sister appears to have produced no male progeny, only a daughter, Johanna, Lady Vernon. During the minority of Thomas, Coity briefly escheated to the King, under the hand Isabel Despenser, seemingly in her capacity as Lord of Glamorgan, she being the wife of Richard de Beauchamp, Lord of Bergavenny,

Gamage

Thomas de la Bere died as a minor on 28 October 1414, following which the lordship reverted to Sarah de Turberville, the youngest sister of Richard de Turberville, who had apparently produced male progeny from her marriage to William Gamage.