Gildesburgh’s antecedents are obscure, but he was certainly related to John Gildesburgh, a London fishmonger of illegitimate birth who died in 1349 possessed of property in the parish of St. Mary Somerset, and to the latter’s ‘uncle’ (?father) Peter Gildesburgh, clerk. Peter had long been in the service of the Burghersh family, and when Bartholomew, Lord Burghersh (d.1355), became ‘magister’ of the Black Prince, he too joined the prince’s entourage, rising to be one of his most prominent officials. He was treasurer of his household 1341-4, clerk of his privy seal 1344-6, head of his exchequer and receiver-general 1347, and in the meantime a member of his council.
During a respite from campaigns overseas, Gildesburgh made an opportune marriage whereby he substantially increased his landed holdings in Essex. Margery Garnet shared her father’s estates equally with her sister, Maud, wife of Sir Thomas Charnels, but after her death Gildesburgh persuaded Maud to let him have the whole of the manor of Wennington and lands at Aveley, Rainham, High Easter and Barnston in Essex, and the manor of Hinxworth and lands at Ashwell in Hertfordshire, to hold for the rest of his life.
In 1364 Gildesburgh acted as an attorney for Lord Burghersh’s cousin, Sir Walter Paveley KG, while he travelled overseas, and from 1365 he served as a trustee of Burghersh’s estates in Sussex, Herefordshire, Wiltshire and elsewhere. In return for his support, Burghersh granted him for life the Essex manor of Bexfields in Chelmsford, and when, in 1366, he personally presented to Urban V at Avignon a petition for the privilege of plenary remission of sins for certain named friends of his, they included Gildesburgh, his second wife and her parents. Three years later Gildesburgh was named as an executor of Burghersh’s will, and he was long engaged with Paveley on that business. He remained a friend and counsellor to the widowed Margaret, Lady Burghersh, acting on her behalf in a bid to persuade Sir Thomas Hungerford to stay in her service and to cease his suspicious dealings with regard to the Burghersh lands in Wiltshire. His friendship with Paveley, who died in 1375, led to a concern for the interests of his son, another Sir Walter (d.1379).
Certain of the properties Gildesburgh had acquired through marriage were held of Humphrey de Bohun, and after the death of Burghersh he entered that nobleman’s service. Having taken part in the naval expedition led by Hereford in the summer of 1371, he evidently caught the earl’s personal attention, for he was then granted by him for life the manor of Nuthampstead (Hertfordshire) and, probably on a short lease, the de Bohun manor of South Fambridge (Essex) as well. Furthermore, in December 1372 he was named as an executor of Earl Humphrey’s will; and two years later he obtained custody at the Exchequer of Pleshey castle and other de Bohun properties in Essex during the minority of the late earl’s two daughters. Others of the circle of former de Bohun retainers with whom he long remained on intimate terms were Sir Thomas Mandeville and the brothers Sir Henry and Thomas Coggeshall.
After Hereford’s death Gildesburgh found a new lord in Thomas of Woodstock, earl of Buckingham, who married Eleanor, one of the de Bohun heiresses. He was knighted in August 1378 while serving under Walter, Lord Fitzwalter, in Woodstock’s retinue on the expedition to Brittany. When first returned to Parliament in 1380 he was thus a seasoned veteran of the French wars and he had some experience of local government (even though he had taken out letters patent exempting him from such employment in 1366 and 1378). That, despite his lack of familiarity with the workings of the Commons, he was elected Speaker may be attributed to his acquaintance with former retainers of the Black Prince who were prominent in Richard II’s household, although he more probably owed the Speakership to his position as a retainer of the earl of Buckingham, whose expedition to France was to cause the House in both this and the next Parliament much concern, not least because of the necessity for taxes to finance the army. Before the dissolution and in response to the Commons’ demands, a commission was set up to investigate the state of the royal household. Gildesburgh was one of six of their number appointed to this body, and in June he was among those appointed to act as receivers of the parliamentary subsidies allocated for the wages of Woodstock’s soldiers. When another Parliament was assembled in November he was re-elected as Speaker and as such asked for a clear statement of the amount needed for the army then about to spend the winter in Brittany. Eventually the Commons granted a poll tax and subsidies assigned specifically for the earl’s support.
In 1384 Gildesburgh accompanied Woodstock on John of Gaunt’s unsuccessful expedition into Scotland. He continued to be closely associated with other members of his lord’s circle, acting as feoffee of the estates of Woodstock’s adherent, Lord Fitzwalter (d.1386), as surety for his lieutenant as constable of England, Sir Matthew Gournay, and as co-feoffee of property in Essex with his mother-in-law, Joan de Bohun, countess of Hereford. He was also recorded in the company of Thomas Feriby, archdeacon of Ely, who was Woodstock’s chancellor. In 1387 Gildesburgh shared a grant at the Exchequer of the keeping of Hornchurch rectory and other property in Essex, Kent and London, belonging to the hospital of Montjoux in Savoy. His return to his fifth Parliament, the Merciless Parliament of 1388, probably owed much to his connexion with Woodstock (now duke of Gloucester) who as one of the Lords Appellant then had control of the government. His fellow shire knight and friend, Thomas Coggeshall, was also of that affinity. Among those executed by judgement of the Parliament was Sir James Berners (in whose estates Gildesburgh had long had an interest). During the recess he was appointed with the sheriff of Essex to take from the local notables oaths in support of the Appellants.
It was now, and probably owing to failing health, that Gildesburgh made settlements of his estates. Among his feoffees were Sir Thomas Hungerford, his one-time fellow retainer of Lord Burghersh, as well as Thomas Feriby and Thomas Coggeshall, both retainers of his present lord, Gloucester. In February 1389 he applied for a royal licence to grant land to Barking abbey, but by the time inquiries were held locally, on 10 Oct., he was dead. He was buried with his first wife and their two daughters in Wennington church. Gildesburgh’s widow, Elizabeth, obtained confirmation from his stepson, Henry Sawtre, of her interest for life in Wennington and other properties pertaining to the Garnet inheritance,