The identity of Dartmouth’s second representative in the Parliament of 1433 cannot be established with absolute certainty. While the sheriff’s indenture names Yon, the composite schedule listing all the men returned throughout the county suggests that it was the more experienced Thomas Asshenden I* who represented the borough in that year.
Yon, who normally lived in a tenement by the Kingsway, held a total of ten messuages and other property in Dartmouth, Southtown Dartmouth and Kingswear.
On other occasions, too, Yon’s title to his acquisitions was called into question: like Stanbery and Cleve before him, John Baron, another Exeter merchant, challenged his possession of a share of a vessel called La Marie, which Yon claimed to have acquired legitimately in the court of admiralty.
Yon was respected among his fellow burgesses, as the frequency with which he was called upon to witness local deeds, appraise contraband or to act as an executor amply testifies. The men with whom he was thus connected included many of the leading men of the town. Apart from Stebbing, who had been his business partner in 1431 and took his side in his dispute with Robert Hill*, he was at one point or another associated in various transactions with Robert Steven*, John Walsh alias Gregory*, Robert Wenyngton*, Richard Carswill, Robert Bowyer and John Brushford*, all of whom in their turn served as mayors of Dartmouth.
By the mid 1420s, Yon was sufficiently established in Dartmouth to secure election as one of the town’s bailiffs. Perhaps in this capacity, he attracted the attention of the Crown, and on relinquishing office was promptly appointed one of the customs collectors in the south Devon district of Exeter and Dartmouth. He may have carried out his official duties to satisfaction, for in the course of 1431 he was included in a number of ad hoc commissions in his locality.
By the time of Yon’s election as bailiff of Dartmouth he was probably married. His wife’s paternity has not been discovered, but it seems that she was in some way related to the Hills of Shilston, for by the later 1420s Hugh was in dispute with Robert Hill over property rights within the manor of Shilston. Hill accused Yon and his associate Stebbing of forging a series of charters relating to the descent of Shilston and publicizing their contents, in breach of the statute of forgeries of 1413, as well as breaking into his close and houses within the manor and threatening his tenants. There can be no doubt that Yon was guilty as charged, for he attempted to escape conviction by a series of legal manoeuvres, securing two writs of protection for planned voyages to France in the retinues of Sir John Radcliffe* and the duke of Bedford, but never set out on either expedition. Once the writs had been annulled, Yon was duly convicted in early 1433 and condemned to pay the huge sum of £200 in damages, but it is probable that his decision to seek election to Parliament later that year was motivated by the intention to influence proceedings at Westminster in person, and in this he succeeded, for the justices of common pleas did not simply confirm the verdict reached at Exeter, but set a separate day for their judgement in the autumn. A further delay ensued, as Yon had failed to provide his attorney, William Kirkesby*, with the requisite warrant, but there was no further question of a challenge to Hill’s title to his manor.
Little is known of Yon’s final years. In early 1447 the abbess of Syon accused him of having taken her goods worth £10 at Sidmouth. No details of the case have come to light, and it is possible that the supposed offence dated back to his time as customs collector.
