The church of St Nicholas stands in the Market Place, alongside the west gateway of the abbey precinct. The W front and N wall date from the mid 12thc., but no original sculpture survives. The present W doorway belongs to a restoration of 1880, and is based on drawings by H.Neil (1804, engraved by J.C.Smith and published in 1805), and J.Storer (1808, engraved by the artist). These show the doorway in a dilapidated state, but substantially as it appears today, with the exceptions noted below.

The church was built as part of the abbey, for the use of lay officials, abbey servants and visitors, and its position straddling the precinct wall reflects this marginal function. It had no parish until 1372, when an appeal to the Bishop of Salisbury resulted in the provision of one, carved out of that of the town church of St Helen's, but fragmented and mostly made up of the abbey granges. The income from this was certainly not enough to support both a rector (a sinecure anyway) and a vicar, and the two posts were combined in 1410. Ultimately even this failed to work, and after 1508 the cure of souls was taken over by the vicar of St Helen's, although most of the income went to the rector of St Nicholas', Thomas Randolph, whose efforts were largely taken up by his work as a prebendary of St Paul's Cathedral.

Pevsner (1966) and Tyack (2010) describe the W doorway as late Norman but much restored. The N jamb capitals, if reliable, suggested a date c.1180-1200.