Nothing is known about Thornbury’s early life or background, although since his son, Sir Philip, was claimed as a kinsman by Thomas Field, dean of Hereford (d.1419), we may reasonably assume that he was related not only to this influential royal clerk and diplomat, but also, albeit distantly, to the latter’s even more distinguished uncle, John Prophet, clerk of the Council to Richard II. The MP certainly spent his youth in some part of the Welsh marches. The alias of Wenlock by which he was known as late as 1380 suggests that he may have come originally from Shropshire. On the other hand, the possibility of some family connexion with the Gloucestershire town of Thornbury is borne out by later references to him as a resident of the diocese of Worcester, within which Thornbury lay.
Although somewhat overshadowed by his more colourful compatriot, Sir John Hawkwood, Thornbury clearly stood high in the esteem of Gregory XI, whose lavish praise of his ‘strenuous labours’ against ‘the damned, pestiferous and cruel tyrants’ was, even so, offset by a marked reluctance to settle any outstanding accounts. From the time of his enlistment in the papal army, which occurred well before January 1373, until he returned to England with a knighthood some four years later, Sir John found it increasingly difficult to secure payment for himself and his men. By June 1373 he had become a marshal of the English forces in Italy, but despite the frequent promises of remuneration made to him during the course of important expeditions to Piacenza and Parma and other missions of a highly confidential nature, no rewards were forthcoming. By April 1375 his troops were beginning to lose the ‘filial patience’ so strongly enjoined upon them by the Pope: the threat of wholesale desertion produced its desired effect, and in the following June Sir John was granted the castle of Montalto and its appurtenances in Ancona. Dissatisfaction with his paymasters at the Curia may have led him to abandon the life of a mercenary. He was back in England by the spring of 1377 when his first action was to secure royal letters of pardon and thus insure himself against the consequences of his somewhat irregular conduct overseas. At least 15,625 florins were then still due to him for services in the Romagna, as well as a further 11,700 florins which he claimed in compensation for spoils surrendered by him and his troops. A substantial amount of the former sum was assigned to him directly from the papal revenues collected in England (where he obtained priority over other creditors), but Pope Gregory refused to honour the other debt without submitting the matter to arbitration. Sir John was also owed money by other English soldiers, such as Philip, younger son of Roger, Lord Beauchamp of Bletsoe. The latter’s will of December 1379 made specific provision for the discharge of certain obligations by which the young man ‘was bound to a knight in Lombardy named Sir John Thornbury’.
Yet whatever his problems in this respect, Sir John did not lose either financially or otherwise as a result of his Italian venture. Not long after his return, he made a compact with the King’s yeoman, William Gold, who appears to have been his companion-in-arms in the papal army, whereby the survivor of their partnership was to receive one third of the other’s goods. Since Sir John died a few months after his friend, neither party benefited from the arrangement, but his executors went to law for the recovery of an estate worth 4,200 marks, most of which was eventually handed over to them by Gold’s Italian agents.
all seditions, adhesions to the King’s enemies and favour shown them, within or without England, captures or deliveries of towns, castles and fortresses without licence, breaches of truces and safe conducts, sales of castles, cities, etc., in England, France, Brittany and Gascony, violations of the King’s Seal, and all other offences against the Crown and the Common Law or in the King’s wars and for all captures of ships on the high seas and in port in time of truce.
CPR, 1377-81, p. 484.
This date marks a significant turning point in Thornbury’s life, for he had by then decided to purchase estates in Hertfordshire and involve himself in the affairs of the local community. His reasons for leaving the diocese of Worcester (where he had been living since his return from Italy) are now obscure; but by the end of 1380 he had acquired the manor and advowson of Little Munden, together with land at Watton-at-Stone and Bennington. He subsequently bought a knight’s fee at Pillerton; and in 1383 Sir Alexander Walden sold him his manor of Bygrave, perhaps reluctantly, for one of his relatives had been murdered there not long before. After this date, Sir John was content simply to consolidate his property: he obtained a grant of certain franchises at Little Munden from Richard II in 1385 and in the following year received permission from the King to crenellate two of his houses at Bygrave.
Until the very end of his life, Thornbury was able to profit from his wide range of military experience, being appointed to various commissions of oyer and terminer set up to examine appeals in the courts of the admiral and constable of England. By November 1388, he had risen to become a knight of the body to Richard II, and presumably sat as such in the Parliaments of 1390 (Jan.) and 1391.
Sir John died not long before 4 Sept. 1396 and was buried in the church of Little Munden. He left only one son, Sir Philip, although the Thomas Thornbury who served on the Hertfordshire bench between 1392 and 1394 may also have been one of his children. Both his daughters were called Joan, and are thus easily confused. One (d. 1418) married successively William Peyto, John Knightley and Sir Robert Corbet, Sir John’s colleague in the Parliament of 1385. The second (d.1449) had two husbands, William Greville of Chipping Campden, Gloucestershire, and Sir Edward Benstede.