The church dates from the twelfth century onwards and was formerly a large building of which now only about half remains. The existing church comprises the nave and south transept of the original building. The quire, north transept and east end were lost in the mid-seventeenth century.

Records show that a small church stood on this site in 1150, and a few years later the nave was widened, the chancel extended, and building of the east and two western towers began. North and south aisles were added in the early thirteenth century, and the transepts added in the mid-fourteenth century. (Only the south transept now remains). A further north aisle was also added around that time, which caused the roof of the small north aisle to be raised above the north clerestory windows. On the south side of the church four Chantry Chapels were added in the late fourteenth century. The most western, or St Mary Chapel is now used as a baptistery. A south porch with parvis was also added in 1396. The construction of the quire began in the early fifteenth century and was completed in 1450. It was 90 feet long and 52 feet wide with two aisles and five bays. In 1645 during the Civil War, cannons were used to attack the Castle nearby, the bombardment lasting several days. The result was that the quire was severely damaged, but it was never rebuilt. Only some fragments of the east end remain in the churchyard.

By the mid-19th-century the church was full of box pews, galleries, flying staircases, and cupboards, and the south transept became a school, blocked from the church. In 1848 restoration commenced under the direction of Ewan Christian, and the church reopened in 1850.

The church today consists of nave, north arcade of six bays with round piers, south arcade, clerestory and outer north aisle with octagonal piers, south porch, south chapels with tunnel vaults, south transept, and chancel (which is the base of the original crossing tower).

In 1993 work commenced to install a toilet, renew the heating system, set up a refreshment point in the south west tower, build a new choir vestry, screen the lady Chapel and improve the north aisle area.

The church has numerous stained-glass windows and a two manual organ.