With the exception of Worcester, no English see was left in the hands of a native bishop. They were held either by Normans or by the Lotharingians who had been appointed in the Confessor's reign. At Worcester, Wulfstan, though not a man of learning, was allowed to retain his bishopric on account of his holiness. Among his other good works, he preached in Bristol against the slave-trade with Ireland that was largely carried on there, and persuaded the townsmen to give it up. Most of William's bishops were men of high character, for his appointments were free from simony, and were, no doubt, suggested by Lanfranc; and the king himself had no liking for evil men. Some of them were learned; nearly all were magnificent. They did not play a great part in State affairs, and stand in some contrast both to the old native bishops, who were leaders of the witan, and, though several of them had been the king's clerks, to the bishops of a later period, who were before all things royal ministers. They generally rebuilt their churches in the Norman style, of which the Confessor's church at Westminster was the earliest example in England. At York, Archbishop Thomas did away with the discipline introduced by Ealdred, and assigned separate prebends to each of the canons, an arrangement which was gradually adopted in all cathedral churches with secular chapters. That the chapter of a cathedral church should consist of monks was extremely rare except in England, but as the Normans generally were strong supporters of monasticism, this was a peculiarity of which they approved, and in some churches secular canons were displaced by monks. Some of the bishops, however, who were not monks, with Walchelin, bishop of Winchester, at their head, saw that monastic chapters were a hindrance to the bishop, and were unfitted for their duties. They conceived the idea of replacing the monks by secular canons even in the metropolitan church. William is said to have approved of the scheme; but it was highly distasteful to Lanfranc, "the father of the monks," and he obtained a letter from Alexander II. indignantly forbidding it. The scheme was defeated, and Walchelin, who had forty clerks with their tonsure cut and their dress prepared as canons, ready to take the place of the monks of St. Swithun's, and to divide the monastic estates into prebends, had to send them about their business. Although William's Norman bishops were generally good specimens of continental churchmen, they had no sympathy with the thoughts and feelings of their clergy and people. Of one only, Osbern of Exeter, it is said that he adopted the English mode of life. Lanfranc despised the national saints, and doubted the right of his predecessor, AElfheah, to the title of martyr, until he was taught better by Anselm, abbot of Bec. The admiration of the Normans for monasticism caused a considerable increase in the practice of endowing monasteries