Tregarthen’s parentage and much of his early career are obscure, but he is known to have trained in the law at Lincoln’s Inn. The extent of the family estates is similarly uncertain, but they centered on the Cornish manor of Tregarthen and also included some 700 acres of land in Trevalscoys and Nansframan in the same county.
Meanwhile, Tregarthen’s links at court had brought him further reward when in November 1448 he and William Bryan, a fellow King’s serjeant, were granted the reversion of the offices of gauger in the port of Bristol and of water-bailiff in Dartmouth. The grant of a reversion rather than the office itself was a symptom of the financial crisis the Crown faced at this date. Parliament had not met since early 1447, and an assembly willing to provide a generous grant of taxation was badly needed. When Parliament was finally summoned to meet in February 1449, the government had an interest in seeing its supporters returned wherever possible, and prime targets in this exercise were the boroughs of Cornwall, where Trevelyan presided over the elections as county sheriff. Tregarthen was duly returned for Liskeard, a place well-known to his patron, who was parker there. Nothing is known of his actions while in Parliament, but he was either still in London or returned there in the autumn. His absence from the West Country was a fortuitous one, for on 27 Nov. an Aragonese galley owned by one Francisco Jungent was driven into Plymouth by a storm, and its cargo, said to be worth more than £12,000, promptly carried off by local men. Tregarthen was accused of having been involved, but protested that not only had he been in the capital at the time of the crime, but when he had learnt that some of the stolen goods had been acquired for his use, he had immediately handed them over to the attorney of their rightful owners. Furthermore, the said attorney had come to him at Lincoln’s Inn and begged his assistance in persuading the men of the south-west to make restitution, which he had readily agreed to do. Indeed, as a result of his efforts, so he proudly claimed, one of the pirates involved had been arrested, brought to London and imprisoned in the Marshalsea.
Although never formally convicted of direct participation in this act of piracy, Tregarthen now faced other difficulties. The Commons’ impeachment of the duke of Suffolk and his subsequent murder spelled trouble for those associated with his regime, and Tregarthen’s close ties with Trevelyan, who was himself targeted, gave him cause for concern. Although he managed to retain his office as stannary bailiff for the remainder of the 1450s, he gained no further office or reward, and the Yorkist ascendancy from the summer of 1460 proved his final undoing. The victors had not forgotten to whom Tregarthen owed his advancement, and stripped him of his offices. Seeing his loss of influence, various men sought to settle old scores. Within weeks of the decisive Yorkist victory at the battle of Towton on 20 Mar. 1461 armed servants employed by Henry Bodrugan† entered Tregarthen’s estates, carried off goods worth 500 marks and occupied land at Pollakka, which he had acquired from Bodrugan in 1448. Tregarthen’s petition to the chancellor for a commission of inquiry fell on deaf ears, for Bodrugan was one of the new government’s trusted supporters in the region and was regularly appointed to such bodies. It took a few years for the matter to be settled and Tregarthen was sufficiently reconciled to Bodrugan as to attest deeds for him.
After securing a royal pardon from Edward IV in 1462, Tregarthen recovered some of the confidence of the government and was appointed to a commission of inquiry in 1464. He probably followed Trevelyan’s lead in providing no more than lukewarm support, if any, for the restored Henry VI in 1470.
Nothing is known for certain of Tregarthen’s attitude to the ursurpation of Richard III, but as much as a result of his old Lancastrian sympathies as of his increasing proximity to the Arundells of Lanherne, who had faced forfeiture under Richard, he may have favoured the accession of Henry Tudor, for within weeks of Bosworth the new King added him to the Cornish bench, where his son was to join him in February 1486. It was probably also in the new reign that he was elected one of the coroners of Cornwall.
