The north aisle was originally Norman, and small round-headed windows still remain to light the triforium. In the angle formed by the aisle and the north wing of the transept stood formerly a two-storied building, the upper part of which communicated by a staircase with the north aisle, but all this has been destroyed. The north transept is chiefly Norman in character, with a fine arcade of intersecting arches beneath a billeted string-course. An excellent Norman turret of four stages runs up at the north-east angle, and is richly decorated, the third story being ornamented with a lattice-work of stone in high relief. East of the transept was once an apsidal chapel, similar to that still remaining in the south arm of the transept, but about the end of the thirteenth century this was destroyed and two chapels were built in its place. These contain beautiful examples of plate tracery windows.
Above these chapels is a chamber supposed to have been the tracing room wherein various drawings were prepared. The compartment has a window similar in style to those in the chapels below.
East of the transept is the choir, with a clerestory of four lofty Perpendicular windows of four lights each, with a bold flying buttress between the windows.
The whole of this part of the church is Perpendicular, the choir aisle windows are very low, and the curvature of the sides of the arches is so slight that they almost appear to be straight lines. The choir roof is flat, and is invisible from the exterior of the church. It is probable that at one time a parapet ran along the top of the clerestory walls, similar to that on the aisle walls, but if so it has disappeared, giving this portion of the choir a somewhat bare appearance. The Lady Chapel is to the east of the choir and presbytery, and contains three large Perpendicular windows on each side; part of the central window on the north side is blocked by an octagonal turret containing a staircase leading to St. Michael's Loft, a large room above the Chapel. The large eastern window of five lights is Perpendicular. The original purpose of the loft above the Chapel is uncertain, and it has been used for a variety of purposes. It was described as "St. Michael's Loft" in 1617, and in 1666 the parishioners petitioned Bishop Morley for permission to use it as a school, describing it as having been "heretofore a chapter-house". The loft is lighted by five two-light windows having square heads and with the lights divided by transoms. The eastern wall has a window of three lights. Very curious are the corbels of the dripstones and the grotesquely carved gargoyles. The south sides of the Lady Chapel and choir correspond very closely with the north. This portion of the church is not so well known as the north side, as private gardens come close up to the walls.
The Norman apsidal chapel still remains on the eastern side of the south transept. This has a semi-conical roof with chevron table-moulding beneath it, and clusters of shafts on each side at the spring of the apse. Of the two windows one is Norman and the other Early English. On the northern side of the apse is an Early English sacristy. The south side of the transept was strengthened by three buttresses, and contains a depressed segmental window much smaller than the corresponding window of the north transept. The south side of the nave has, externally, but little interest as compared to the north side, for the cloisters, which originally stood here, have been pulled down. Traces of the cloister roof can still be seen, also a large drain, and an aumbry and cupboard built into the thickness of the wall. There are also the remains of a staircase which probably led to a dormitory at the western end.
In the south wall of the nave are two doors, that at the west used by the canons, and that at the east by the Prior. The latter door is of thirteenth-century date and is distinctly French in character.
In mediæval days the nave was used as the parish church, and had its own high altar, while the choir was reserved for the use of the canons. The nave is made up of seven noble bays; the lower arcade consists of semicircular arches enriched with the chevron ornament, while the spandrels are filled with hatchet-work carving. The triforium of each bay on both sides consists of two arches supported by a central pillar and enclosed by a semicircular containing arch, with bold mouldings.
The clerestory was built about 1200 by Peter, the third Prior. The present roof is of stucco, added in 1819; the original Norman roof was probably of wood, although springing shafts exist, which seem to indicate that a stone vault was contemplated by the Norman builders. The north aisle retains its original stone vaulting, put up about 1200. This aisle is slightly later than the southern one, which was completed first in order that the cloister might be built. The windows are of plate tracery, and mark the transition between Early English and Decorated. The south aisle is very richly decorated with a fine wall arcade enriched with cable and billet mouldings. The vaulting is of the same date as that in the north aisle, and is also the work of Peter, Prior from 1195 to 1225. In the western bay is the original Norman window, the others being filled with modern tracery of Decorated style. In this aisle is a large aumbry and recess, where the bier and lights used at funerals were stored. There is also a holy-water stoup in the third bay. At the west end are the remains of the stairway which led to the dormitory. The stairway is built into the wall, which, at this particular spot, is nearly seven feet thick.
Under the north transept is an early Norman apsidal crypt with aumbries in the walls. There is a corresponding crypt in the south wing.