The church was entirely rebuilt and enlarged in the 15th century, and no detail now remains of the former nave and chancel, which appear to have been added to from time to time. The north aisle was the earliest addition, then the two east bays of the south aisle and the west bay of the south chapel; shortly afterwards the south aisle was extended westwards the full length of the nave and the south chapel eastwards to the east wall of the chancel; the west tower was erected about the close of the 15th century, the north chapel and vestry are dated 1522, and the south porch was added in the early 17th century. The north chapel and vestry, both built in 1522, have an ornamental parapet carried round outside on which is carved the inscription "Pray for the welfayr of Syr Wylyam Say knyght wych fodyd yis chapel in honor a ye trenete the yere of our Lord God 1522." Stags heads and traceried panels with the arms of Say are carried at intervals above the parapet; the upper parts of the panelled and crocketed buttresses are set diagonally.
On the south side of the chancel is the Purbeck marble altar-tomb of Sir John Say and his wife, Elizabeth Cheyne. The sides of the plinth are panelled and traceried panels, three of which contain shields which retain some of their original colouring. On the moulded slab are fine brasses of the knight and the lady; the knight is in plate armour with surcoat charged with his arms, the figure is now headless. The lady wears a sideless surcoat and a mantle charged with her arms. The figures are elaborately engraved and retain much of the original coloured enamelling. Two shields still remain with the arms of Say, and a brass inscription, parts of which are missing, runs round the margin. On the north side of the chancel is the altar-tomb of Sir William Say, the builder of the north chapel; it is of early 16th-century date. The plinth is ornamented with square moulded and cusped panels set diagonally, in which are shields bearing indents of missing brass figures. On the plinth is a slab of Purbeck marble. Above the tomb, supported on octagonal columns, is a canopy, the soffit carved with pendants and fan vaulting; under the east end is a slab with indents of a knight and a lady.