The Norman church, finished as we have seen in 1088, stood without change for rather more than a century. Then changes began. Abbot John de Cella (1195-1214) pulled down the west front and began to build a new one in its place. He laid the foundation of the whole front, but then went on with the north side first. The north porch was nearly finished in his time; the central porch was carried up as far as the spring of the arch; the southern porch was carried hardly any way up from the foundations.[5] The porches are described by those who saw them before Lord Grimthorpe swept away the whole west front as some of the choicest specimens of thirteenth-century work in England. The mouldings were of great delicacy, and were enriched with dog-tooth ornament. It is said that Abbot John was not a good man of business, and that he was sorely robbed and cheated by his builders, and so had not money enough to finish the work that he had planned. To his successor, William of Trumpington, it therefore fell to carry on the work. He was a man of a more practical character, though not equal to his predecessor in matters of taste. He finished the main part of the western front. Oddly enough no dog-tooth ornament was used in the central and southern porches, and the character of the carved foliage differs also from that of the north porch. In Abbot John's undoubted work the curling leaves overlap, and have strongly defined stems resembling the foliage of Lincoln choir, while that of Abbot William's time had the ordinary character of the Early English style. There is evidence to show that he intended to vault the church with a stone roof; this may be seen from the marble vaulting shafts on the north side of the nave between the arches of the main arcade, which, however, are not carried higher than the string-course below the triforium. The idea of a stone vault was, however, abandoned before the two eastern Early English bays on the south side were built, for no preparation for vaulting shafts exists there. [5] Sir Gilbert Scott was of the opinion that the south porch was also John de Cella's work. Abbot John de Cella had begun to build afresh the western towers, or, according to some authorities, to build the first western towers that the church ever had; we have no record of their completion, and it is said that Abbot William abandoned the idea. We have only the foundations by which we can determine their size. William of Trumpington transformed the windows of the aisles into Early English ones. He also added a wooden lantern to the tower, somewhat in the style of the wooden octagon on the central tower of Ely.