The choir was only 80 feet long, reaching to the end of the present stalls. Eastward it terminated in an apse. Its width can be judged from traces of the original roof, still perceptible in the west wall of the present choir. In accordance with a frequent arrangement, the ritual choir extended westward of the crossing, and included the two eastern bays of the nave. In the centre was a low square typical Norman tower, 35 feet square, of which the lower parts of the piers remain. To allow for the extension of the ritual choir the eastern and western arches of the crossing were carried on corbels. White or grey sandstone from quarries in the district was used in the construction of the minster, perhaps supplemented by stones from the Roman wall. Stucco was applied to the exterior, red lines marking the joints. There is no doubt that this stucco has materially helped to keep the Norman stone-work in a good state of preservation. It will be seen then that the original church was a Norman minster, of moderate size, consisting of a nave, with north and south aisles, a small choir, a low square tower, and north and south transepts. Thus it remained till about 1250, when, as usually happened, the clergy became dissatisfied with the smallness of their choir, and a new one was projected on a much larger scale. Its length was to be equal to the nave, while in height and breadth it was to be greater. The increased length allowed room for the ritual choir on the east side of the crossing. Any extension of the cathedral on the south was prevented by the presence of the conventual buildings: therefore the north choir-aisle was thrown into the choir, and a new one added northward of the former. One consequence of this alteration is seen by comparing the entrance to each aisle. That of the south choir aisle is the original Norman arch, while the entrance to the north aisle is a beautiful late thirteenth-century arch (Decorated). The corresponding Norman arch of the north aisle has been blocked up, but is still easily traced. Another consequence is, that the extension having taken place on one side only, the eastern arch of the tower fills but a part of the west end of the choir. The choir arch consequently is symmetrically placed with regard to the roof of the nave, but not with the choir roof; and the central line of the choir does not coincide with that of the nave; for, though the south wall of the choir is in a line with the south wall of the nave, the choir being 12 feet broader than the nave, the axis of the former is to the north of the axis of the nave. The view from the east end looking towards the nave is quite spoiled by this want of symmetry.