Church of St. Nicholas was founded in 1098, as a monastery church owned by the Seez Abbey in Normandy. It developed to the times of the English – French Hundred Years War, when foreign monasteries in England were sequestered and finally closed in 1414. It was then administered by the royal administrator until he gave the church and monastery to the abbey in St Albans in 1443. After 1532, when all the monasteries were dissolved due to the Reformation, the church of St. Nicholas was transformed into a parish church, and the rest of the buildings fell into disrepair. In the years 1879-1895 a thorough renovation of the monument was carried out.
The medieval church consisted of a long, 13th-century nave to which the entrance led from the south through a vaulted porch. The temple originally had two transepts, from which the south in the fifteenth century was rebuilt to the base of the tower. The eastern side of the church was ended by the 14th-century chancel and parallel to it the north-eastern chapel and the northern sacristy. The southern tower is topped with a parapet on corbels and battlement, from the south-west side it has a turret with a staircase. Its large window and entrance portal from the south are 19th-century additions. Also the other southern windows in the nave and the chancel were transformed in the Victorian era. The northern wall of the nave is reinforced with huge buttresses, but earlier probably from that side there were some monastery buildings. Two original windows from the 12th / 13th century have been preserved in this wall.
Website britishlistedbuildings.co.uk, Priory Church of Saint Nicholas A Grade I Listed Building in Pembroke, Pembrokeshire.