As early as 20 Oct. 1279 he wrote to Llywelyn, rebuking him for his infringements of the liberties of the church (ib. p. 77). In July 1280 he visited Wales, and made a friendly arrangement with Llywelyn as to the bishopric of Bangor, receiving a present of some hounds from the prince (ib. pp. 125–6). But a month later a letter of Peckham's, in which he asserted the reasonableness of Edward's claim to settle disputes on the marches by English customs, roused Llywelyn's wrath (ib'. p. 135; see more fully under Llywelyn ab ruffydd). The archbishop's ill-considered action led to the trouble which precipitated the end of Llywelyn's power. By the spring of 1282 the Welsh had broken out into open rebellion, and on 1 April Peckham ordered their excommunication (ib. p. 324). Towards the end of October Peckham joined the king at Rhuddlan, with the intention of endeavouring to mediate in person. On 31 Oct. he set out, against Edward's will, to meet Llywelyn, and spent three days with him at Snowdon. But prolonged discussion and negotiations between the archbishop and the Welsh prince failed to produce any terms to which Edward could give his consent (ib. pp. 435–78, cf. Pref. ii. pp. liii–lvi; Ann. Mon. iv. 289–90). After Llywelyn's death Peckham appealed to the king on behalf of the Welsh clergy (Registrum, pp. 489–91), and, after the completion of the conquest, took various measures intended to bring the church in Wales into conformity with English customs, and also induced the king to adopt some measures for remedying the damage which had been done to the Welsh churches through the war (ib. pp. 724–6, 729–35, 737, 773–82, cf. Pref. ii. pp. lvii–lx).
Peckham's ecclesiastical policy, like his political action, was marked by good intentions, but marred by blundering zeal and an inclination to lay undue stress on the rights and duties of his office. His position at the start was rendered more difficult by financial embarrassments. His predecessor, Robert Kilwardby, had sold the last year's revenues of the see, and had taken away much valuable property (ib. pp. 18, 277, 550). Peckham was consequently without means to discharge the debts which he had incurred for the expenses of his appointment, and, owing to this and the dilapidations of the archiepiscopal property, was much hampered by need of money. He endeavoured without success to recover the property taken away by Kilwardby (cf. ib. pp. 17, 21, 105–7, 120, 172, 1058–60). In his ecclesiastical administration Peckham applied himself with much zeal to the correction of abuses in the church. At the council of Reading in July–August 1279, statutes were passed accepting the constitutions of Ottobon, and forbidding the holding of livings in plurality or in commendam. At the council of Lambeth in October 1281 further statutes were passed to check the growth of plurality, and both councils dealt with minor ecclesiastical matters (Wilkins, Concilia, ii. 33, 51). Much of Peckham's episcopate was taken up with systematic and searching visitations of various dioceses of his province, for the most part conducted by himself in person. Lichfield and Norwich were visited in 1280 (Ann. Mon. iii. 282, iv. 284), the Welsh dioceses and Lincoln in 1284, and Worcester in 1285 (ib. iii. 351, iv. 491; Registrum, Pref. iii. pp. xxvii–xxxv). His insistence on his visitatorial rights had involved him in 1280 in a dispute with the king, and two years later the suffragans of Canterbury presented him with twenty-one articles complaining of his procedure and of the conduct of his officials. Peckham denied some of the allegations, and justified himself in regard to others, but at the same time found it necessary to appoint a commission of lawyers, who drew up regulations intended to obviate some of the complaints (Registrum, pp. 328–39). Nor were Peckham's relations with individual bishops always satisfactory. When William of Wickwaine, the recently consecrated archbishop of York, arrived in England late in 1279, Peckham at once resisted his claim to bear his cross in the southern province (Ann. Mon. iv. 281), even though the pope had expressly commanded him to abstain from a dispute on this matter (Bliss, Cal. Papal Registers, i. 459). When the question occurred again in 1284 and 1285, Peckham maintained the rights of his see with equal tenacity (Reg. pp. 869, 906–8). A more serious dispute was with Thomas de Cantelupe, bishop of Hereford, who complained of the removal of a matrimonial suit to the archbishop's court, and, failing to obtain redress, appealed to Rome (ib. p. 1057). In 1282 a fresh quarrel arose through the excommunication of Cantelupe's official by Peckham. Cantelupe refused to confirm the sentence, and, after an ineffectual meeting at Lambeth on 7 Feb., the archbishop excommunicated him. The bishop appealed to Rome, and on 25 Aug. died at Orvieto; even then Peckham's hostility did not cease, and he attempted to prevent the christian burial of Cantelupe's remains (Reg. pp. 299, 308, 315, 318–22, 382, 393; Ann. Mon. ii. 405). Peckham's visitation of the Welsh dioceses in 1284 involved him in a dispute with Thomas Bek, bishop of St. David's, who set up a claim to metropolitan
