Treouran’s family came from the far west of Cornwall, where they owned property in the parishes of Sancreed, Ruan Major and Grade. Roger’s landed income was nevertheless modest at best, and even allowing for a degree of underassessment is unlikely to have exceeded by much the £5 p.a. at which it was rated in 1451.
In the interim, Treouran had also attracted the attention of the Crown. In the summer of 1433 he was among the commissioners appointed to inquire into an act of piracy committed by the men of Penzance, not far from his home at Driff,
Rather less than of his official appointments is known about Treouran’s private affairs. As was common for men of his standing, he was periodically pursuing minor disputes in the royal law courts. Thus, in 1435 he was engaged in litigation against a group of lesser men from the Helston area for apparent incursions into his property,
The circumstances that led to Treouran’s return to Parliament in early 1449 for the borough of Truro are unclear, but his kinsman John Treouran was of some consequence in the town’s merchant community and may have facilitated the coroner’s election. Moreover, even by this time Treouran may already have been in the service of Alice, dowager countess of Oxford, and one of the heiresses of Sir Richard Cergeaux†, who held extensive estates in western Cornwall, and whom he would serve as her receiver general until her death in May 1452.
It is likely that Treouran’s connexion with the de Vere family played a part in his election for Helston in 1455. Following the death of Countess Alice, he seems to have maintained links with her son the earl of Oxford, and two other members of the de Vere circle, the earl’s brother Sir Robert* and his servant Thomas Gale*, were also returned to Parliament from the south-west that year. Moreover, Treouran was accompanied to Westminster by his son Roger II, indicating beyond reasonable doubt that he had actively sought to be elected.
Little is known of Treouran’s later years. From the second half of the 1450s his interests expanded into Kent, where he was serving as an associate justice of assize about that time, and by the end of the decade he was also employed as a feoffee in that county.
