Sir John, commonly called the Good Lord Cobham, was born in the reign of Edward III. He obtained his peerage by marrying the heiress of that Lord Cobham who had strenuously opposed the tyranny of Richard II.; and, with the estate and title of his father-in-law, he seems to have acquired the patriotic and independent spirit for which that nobleman was distinguished. By his means, the statute against provisors was revived, and guarded with more severe penalties than ever; and he was also one of the leaders of the party who, having drawn up a number of articles against the corruptions which then prevailed amongst ecclesiastics, presented them in the form of a remonstrance to the Commons. He was at great pains in collecting and transcribing the works of Wickliffe, which he dispersed amongst the people; and he sent a number of his disciples as itinerant preachers into various parts of the country. In the reign of Henry IV. he commanded an English army in France, at that time distracted by the contentions of the two factions of Orleans and Burgundy; and, in this capacity, he compelled the Duke of Orleans to raise the siege of Paris. In the reign of Henry V. he was accused of heresy, the growth and extension of which was mainly attributed to his influence. The king having a favour for Lord Cobham, who held a domestic office at court, delayed the prosecution, and kindly undertook, by reasoning and expostulation, to reclaim him from his errors. But the attempt proved abortive. "Next to God," said his lordship, "I protest obedience to my king; but as to the spiritual dominion of the pope, I could never see upon what foundation it is claimed, nor can I pay him any obedience;" and he added, "It is as sure as God's word is true, he is the great Antichrist foretold in holy writ." This answer, so different from what had been expected, deeply offended the king, who, turning away in visible displeasure, with- drew his favour from Cobham, and left him to the censures of the church, which speedily overtook him. Being sum- moned to appear before the archbishop, he disobeyed the citation, and was excommunicated on the ground of contu- macy. Reckless in exposing himself to danger, he seems to have wanted the courage to confront it boldly when it appeared in a definite shape. Hoping to avoid the im- pending storm, he waited upon the king with a confession of his faith in writing; but whilst he was in the royal pre- sence, an officer of the ecclesiastical court entered, and cited him to appear before the archbishop, upon which he was immediately conveyed a prisoner to the Tower. When brought before the proper tribunal, he read his opinion of the several articles in regard to which he supposed that he had been called in question, particularly the eucharist, images, penances, and pilgrimages; but he was informed, that in some things he had not been sufficiently explicit in stating his particular views; that on all these points the church had already decided, and by her determinations all Christians ought to abide; that these determinations would be given him as a direction of his faith; and that, in a few days, he must appear again and state his opinions. The second examination, however, ended like the first. Cobham declared that "he knew none holier than Christ and his apostles; and that these determinations were surely none of theirs, as they were against Scripture." He was accord- ingly condemned as a heretic, and remanded to the Tower; but he contrived to effect his escape from prison, and lay concealed in Wales, until information reached the king at Elyham that about twenty thousand Lollards had assem- bled for his destruction at St Giles, with Lord Cobham at their head. A bill of attainder then passed against him, a price was set upon his head, and a perpetual exemption from taxes promised to any town which should secure him. After having spent four years in Wales, he was at length seized, carried to London, and executed in St Giles's Fields, in December 1417, with circumstances of cruelty characteristic of the times.

As a writer, Lord Cobham is only known by a piece en- titled "Twelve Conclusions, addressed to the Parliament of England," at the end of the first book of which are some monkish rhymes in Latin, which Bale has preserved. "A Breve Chronycle concerning the Examynacyon and Death of the blessed martyr of Christ, Syr Johan Oldecastell, the Lorde Cobham," was also published by Bale, and reprinted under the care of a Mr Lewis of Margate in 1729. Since that time the life of Lord Cobham has been written by Mr Gilpin, who describes him as a person of uncommon parts and varied talents, well qualified either for the cabinet or the field; as possessing acquirements equal to his parts; and, besides, as remarkable for his ready and poignant wit in conversation. "It was his thirst of knowledge," adds his biographer, "which first brought him acquainted with the opinions of Wickliffe. The novelty of them engaged his curiosity. He examined them as a philosopher, and in the course of his examination became a Christian."