Of the priory church consecrated by Robert de Bethune in 1130, only the nave, north aisle and west tower survive. Overall the church consists of the Norman nave with its west tower and north aisle and south arcade. To the south of this arcade stands the south, or parish nave of 1239, and to the south of this an aisle with a six-bay arcade, added in 1320. The original east end had transepts, a crossing tower and an apsidal presbytery with an ambulatory and three radiating chapels (as at Reading). All this work was destroyed after the Dissolution of Reading and its cell in 1539, and a wall was erected as the eastern terminal of what was now the parish church. Most of the monastic buildings were demolished too, although a gatehouse chapel and parts of the infirmary survive (Brown and Wilson 1994). At the west end of the church, the tower was heightened and the great west window added in the 15thc. The design of the 12thc nave arcades is unique. At the lowest level, and from the east, they have a stretch of walling, then three bays carried on cylindrical piers, then a long pier or stretch of walling pierced by a narrow round arch, then a further bay at the west. The second storey was originally a gallery, its openings now blocked on both sides and the gallery floor removed on the south. Above this is a clerestory. Smith (1963) has suggested that it was at first intended to roof the nave with a series of three domes, on the model of Saint-Front, Perigueux, but that this scheme was abandoned. The present roof is flat. Romanesque sculptural decoration is found on the capitals and imposts of the nave arcade, the W doorway, and the W window. These last two are decorated on both the external and internal faces. The nave gallery openings and clerestories will also be described, although they include nothing that could be called sculpture.

The monastery of St Peter, which existed here in the 7thc, was destroyed by the Danes during 9thc. It was subsequently refounded as a secular college and then a nunnery but this had ceased to exist by 1046. The manor of Leominster was held by Edith, Edward the Confessor’s queen, and had reverted to the Crown by 1086. In 1123 the manor and the (ruined) church were given by Henry 1 to his newly founded abbey of Reading. Thus Leominster became a Benedictine priory and a cell of Reading.

Soon after 1130 four altars were dedicated, suggesting that at least the presbytery and the transepts were ready at that time. One of the altars mentioned is that of the Holy Cross and the usual position of that altar was at the E end of the nave, in front of the pulpitum. During the C13th and later, the church was enlarged southwards, when the original S aisle was replaced by a more spacious one. After the suppression of the monasteries in 1539, the monastic buildings (to the N and NE of the church) were demolished and also the presbytery, the transept and the crossing tower. The nave then became the parish church. There was a major restoration of the building by G G Scott in 1866 and 1878-9 and of the W tower in 1891. Excavations in 1853 and 1932 revealed the plan of the E end of the church, which consisted of a presbytery with an ambulatory and the three radiating chapels, the central of which was later replaced by a rectangular Lady Chapel. The transept arms each had an apsidal chapel to the E. The plan of the E part of the church was thus modelled on that of Reading Abbey.

The sculpture of the priory has long been recognised as the work of the Herefordshire School, since the capitals of the W doorway are clearly by a sculptor who also worked at Shobdon, Kilpeck and some other places in the region. Leominster provides evidence that not only does the sculpture of the school owe a debt to Aquitaine but here the architectural design, as originally intended, was also inspired from that region of France. The nave arcades are based on Saint-Front, Perigueux, the facade with its doorway and very large window above it, flanked by buttresses are modelled on Fontevrault Abbey while the pointed arch of the W doorway has numerous parallels in Aquitaine. As can be expected, some elements of the sculptural decoration are derived from Reading Abbey. The "dart-leaf" motif resembles the decoration of several of the imposts of the Reading capitals, the stalks of foliage penetrated by other stalks, a very rare device, is found in both Reading and Leominster, and the assiduous researcher will soon discover other similarities of detail. Thurlby (1999) provides detailed comparisons with other sculpture at Herefordshire School sites. It has been suggested (Jonsdottir, 180) that Leominster was the earliest work of the Herefordshire School but this is certainly wrong. Both Shobdon Priory (c1125-30) and Kilpeck (c1130-5) are earlier. The nave of Leominster was built after c1130 (the date of the dedication of the altars) and the facade cannot be earlier than c1140-50.

A short distance S of the priory church, in the garden of Grange Court are some carved stones, evidently from the priory.