Sec. 52. Grantham also provides us with a lengthened nave. The position of its earlier west wall is clearly shown by the masses of masonry which occur between the eastern bay of the new, and western bay of the old, arcade on either side. The responds on the eastern side of these pieces of wall are twelfth century work: on the west side, they belong to the later part of the thirteenth century. Such lengthening was probably very common in later Gothic times, and we may surmise that it took place in many instances where arcades were entirely rebuilt, and no visible trace of the process was left. However, there are many churches in which one or more extra bays have been added to the nave, and the join of the old and new work is marked as at Grantham. Whaplode church in south Lincolnshire had its early twelfth century nave lengthened by three bays about 1180. At Colsterworth, near Grantham, a western bay was added to the nave about the same time, and an earlier north aisle lengthened. Above the piece of wall which occurs between the older and newer work, the quoins of the aisleless church remain entire. Usually, as at Grantham, the lengthening of the nave was undertaken in connexion with a new western tower, which was built up outside the church, and then connected with it by one or two bays of arcading. Almost contemporary with the tower and spire of Grantham are those of Tilney All Saints, near Lynn. Here a single bay was added west of the late twelfth century nave; and, as no new aisles were contemplated, the old arcades, with their rounded arches, were left intact. Bubwith in Yorkshire, and Caunton in Nottinghamshire, are later examples of churches where the tower was built west of the end of an earlier nave, and a bay was built to connect it with the older work. Sometimes, as at Gretton in Northamptonshire, where the slope of a steep hill forbade extension far to the west, a new tower was built only a few feet beyond the limit of the old nave. In such a case, the side walls of the nave might be carried solid westwards to meet the tower, or, as happened at Gretton, narrow arches might be made between the tower and the west end of the older wall. The beautiful tower and spire at Oundle were built just outside the west wall of the thirteenth century nave; and were doubtless intended to be followed by a complete rebuilding of the arcades--such a rebuilding as took place at Lavenham in Suffolk, towards the end of the fifteenth century. The idea, however, was abandoned, and the space between the arcades and the tower filled in solid with rather rough masonry. [Illustration: Fig. 13. Gretton, Northants: extension of 12th century arcade to meet 15th century tower.]