Sec. 31. The great majority of Norman rectangular chancels have been lengthened and enlarged; for the plain "altar-house" at the east end of the nave was too small for the purposes of the ritual of the thirteenth and fourteenth centuries, and afforded no intermediate space between nave and chancel. However, short and approximately square chancels were by no means invariable; and, before the middle of the twelfth century, oblong chancels of considerable length in proportion to their width were being built. There is a good early twelfth century example at Moor Monkton, in the Ainsty of York; and the chancel of the middle of the twelfth century at Earl's Barton, Northants, is of considerable depth, and was of ample size for all later purposes. At Earl's Barton the eastern portion was the chancel proper; while the western portion supplied that space for a quire which was not provided in less elongated plans. In by far the larger number of cases, the rectangular chancel had a wooden roof. There is, however, a fair number of churches in which the system of ribbed vaulting, as employed in larger buildings, was used. Thus at Heddon-on-the-Wall, Northumberland, there is a small square chancel with a ribbed vault. At Warkworth, there is a long vaulted chancel of two bays, built during the first quarter of the twelfth century; and at Tickencote, Rutland, two bays are combined in one by the use of sexpartite vaulting. In these cases the chancel arches are wide, forming the western transverse arches of the vaulting: that at Tickencote is of remarkable magnificence. Sec. 32. There are certain cases in which the chancel was of the same width as the nave, and no structural division existed between them. At Askham Bryan and at the chapel of Copmanthorpe, near York, the plan, externally and internally, is a plain undivided oblong. At Tansor, Northants, the chancel was rebuilt about 1140, when the side walls were set back in a line with those of the nave. In St Mary's in the Castle at Leicester, the long and very narrow nave was, as may still be clearly seen, continued eastward without a break into the long and narrow quire and chancel. Here the eastern half was used, no doubt, by the college of dean and canons, while the western half was the parish church. The beautiful church of St Peter, Northampton, built towards the end of the third quarter of the twelfth century, gives us a complete example of an undivided plan, aisled throughout save in the eastern bay, which forms a projecting chancel east of the aisles of the choir.