The church of St Mary was built at the edge of the outer bailey of the castle, and was clearly designed to serve the expanding town.
The 12thc chancel, built in ashlar, has survived later rebuilding campaigns. It is two bays long, vaulted, and was originally decorated on the interior with an intersecting blind arcade, most of which has now been removed. On the exterior, there are pilaster buttresses and the remains of a corbel table, but the 12thc windows have been replaced, probably twice in the case of the E window.
The roof line of the earlier nave, probably 12thc, can be seen on the E wall of the W tower. The W tower also belongs to the 15thc. The chancel was restored in 1852.
The history of the church of St Mary is closely linked to that of St John the Baptist, the church that was built in the inner bailey of the castle, perhaps originally to serve as the garrison chapel, while St Mary's served the town. In 1194-95 the churches are described together as ecclesie, but by 1226-28 they are called capelle. In 1268 John, chaplain of the king's chapel, held both churches. However, there is evidence only for St Mary's holding plots of land in the medieval period (VCH 1975, 285-314).
The date of the present nave is suggested by an inscription in the roof which attributes the work to money provided by William Smythe who died in 1436.
E. Bradby, The Book of Devizes, Buckingham 1985.
Historic England listing: no. 1251640.
N. Pevsner and B. Cherry, The Buildings of England: Wiltshire, New Haven and London 2008, 207-208.
N. Pevsner, The Buildings of England: Wiltshire, Harmondsworth 1975, 205-206.
Victoria County History: Wiltshire, London 1975, 285-314. British History Online http://www.british-history.ac.uk/vch/wilts/vol10/pp285-314 [accessed 4 February 2018]
J. Waylen, Chronicles of the Devizes: being a history of the castle, parks, and borough of that name, London 1839, 309-320.