Courtenay was a younger son of Hugh de Courtenay, 10th Earl of Devon (d. 1377), and through his mother Margaret, daughter of Humphrey de Bohun, 4th Earl of Hereford, was a great-grandson of Edward I.
Having been made prebendary of Exeter, of Wells and of York, he was consecrated bishop of Hereford on 17 March 1370, was translated to the see of London on 12 September 1375, and became Archbishop of Canterbury on 30 July 1381, succeeding Simon of Sudbury in both these latter positions.
As a politician, the period of Courtenay's activity coincides with the years of Edward III’s dotage, and with practically the whole of Richard II's reign. From the first he ranged himself among the opponents of John of Gaunt, duke of Lancaster; he was a firm upholder of the rights of the English Church, and was always eager to root out Lollardry. In 1373 he declared in convocation that he would not contribute to a subsidy until the evils from which the church suffered were removed; in 1375 he incurred the displeasure of the king by publishing a papal bull against the Florentines; and in 1377 his decided action during the quarrel between John of Gaunt and William of Wykeham ended in a temporary triumph for the bishop.
Wycliffe was another cause of difference between Lancaster and Courtenay. In 1377 the reformer appeared before Archbishop Sudbury and Courtenay, when an altercation between the duke and the bishop led to the dispersal of the court, and during the ensuing riot Lancaster probably owed his safety to the good offices of his foe. Having meanwhile become archbishop of Canterbury Courtenay summoned a synod, in London, the so-called "Earthquake Synod", which condemned the opinions of Wycliffe; he then attacked the Lollards at Oxford, and urged the bishops to imprison heretics.
Courtenay was for a short time chancellor of England during 1381, and in January 1382 he officiated at the marriage of Richard II with Anne of Bohemia, afterwards crowning the queen. In 1382 the archbishop's visitation led to disputes with the bishops of Exeter and Salisbury, and Courtenay was only partially able to enforce the payment of a special tax to meet his expenses on this occasion. During his concluding years the archbishop appears to have upheld the papal authority in England, although not to the injury of the English Church.
Courtenay protested against the confirmation of the statute of provisors in 1390, and he was successful in slightly modifying the statute of praemunire in 1393. Disliking the extravagance of Richard II, Courtenay publicly reproved the king; and, after an angry scene, the royal threats drove him for a time into Devon. In 1386, he was one of the commissioners appointed to reform the kingdom and the royal household, and in 1387 he arranged a peace between Richard and his enemies under Thomas of Woodstock, Duke of Gloucester.
https://en.wikipedia.org/wiki/William_Courtenay
https://en.wikipedia.org/wiki/Simon_Sudbury
https://en.wikipedia.org/wiki/List_of_Archbishops_of_Canterbury#After_the_Norman_conquest
https://en.wikipedia.org/wiki/Bishop_of_London#Post-Conquest
https://en.wikipedia.org/wiki/Bishop_of_Hereford#Norman_conquest_to_the_Reformation
https://en.wikipedia.org/wiki/Lord_Chancellor#History
https://en.wikipedia.org/wiki/List_of_Chancellors_of_the_University_of_Oxford .
