St Mary's Church, was formerly a royal free chapel and collegiate, with a dean and twelve canons. It is a large and very fine cruciform building of stone, in the Transitional, Early English, and later styles, with slight indications of Norman work at the west end. It consists of a chancel with five bays, nave with five bays, aisles, transepts, south porch and an embattled central tower containing eleven bells and a clock and chimes.
The whole of the nave and its aisles, and the lower part of the tower, are in the earliest Pointed style, and probably date from the late 12th century. The south transept is of a later date, in the more mature Early Pointed style, the south aisle of the chancel, which has an angle turret, and the chancel itself, are of a later period. The north aisle of the chancel, and the north transept, are Early Decorated style. The upper part of the tower is in the Decorated style and was formerly surmounted by a spire, which was blown down in a storm in 1593-4.
In the late 15th or early 16th century, a clerestory, with richly moulded roof, was substituted for the previous high pitched roof of the nave, and at the same time, a clerestory was added to the north transept.
The church was restored in 1844-5 under the direction of Sir George Gilbert Scott, RA, and during 1877-79 was further restored. In 1887, a carillon playing fourteen tunes, three new bells, and a set of Westminster quarter chimes were fitted in the tower
. The College of St Mary, or College of Stafford, was founded before the Norman Conquest. It was dissolved in the first of Edward VI, and at that time consisted of a dean and thirteen prebendaries, and possessed considerable property, a small portion of which was granted to the Grammar School, by Edward VI, and the rest was granted by Elizabeth I to the Corporation of Stafford, in trust for the support of the rector and curate of St Mary's.