Yerman’s parentage and origins have not been established, but he may have hailed from Sussex, where he held office in the 1440s.
Even if it was Bishop Moleyns who had initially recommended Yerman to the treasurer, Bishop Lumley of Carlisle, he rapidly established himself at the Exchequer, as well as in his region. In the autumn of 1452 he was sent on Exchequer business to the ports of Boston, Bishop’s Lynn, Ipswich and Sandwich, by the new treasurer, the earl of Worcester, receiving expenses of 53s. 4d. He may by this date already have been in the service of the under treasurer, John Wood III*, in which capacity he received assignment for the expenses of the royal household on behalf of its treasurer, John Stourton II*, Lord Stourton, in January 1453.
Nothing is known of Yerman’s activities in the Commons, but during the Easter recess he was granted an Exchequer lease of the manor of Yen Hall in West Wickham in Cambridgeshire (which had been seized pending a settlement of the shrieval account of John Harleston II*) for ten years, at an annual farm of 100s.
While there is no evidence to suggest that Yerman maintained partisan sympathies for the duke of York and his supporters, it may be significant that he secured the clerkship of the estreats during the treasurership of Henry, Viscount Bourgchier (brother-in-law to both York and the duke of Norfolk), in the autumn of 1460. He continued in post after Edward IV’s accession. It was in his official capacity that in the summer of 1462 Yerman came into conflict with the under sheriff of Middlesex, John Toller I*. The background to their dispute is uncertain, but it evidently concerned the summons of the green wax (the estreats of fines arising from proceedings in the common law courts), that it was Yerman’s duty to compile and issue. According to Yerman’s deposition before the barons of the Exchequer and a subsequent petition to the earl of Worcester, in the autumn of 1462 he had issued various summonses addressed to the sheriffs of London on 21 July that year. On the following 3 Aug., he had been summoned by Hugh Fraunceys, one of the ushers of the Exchequer, to speak with Toller in the Exchequer chamber. When he arrived there, Toller had drawn his dagger and arrested him, accusing him of being a traitor, and had threatened to drive him all the way to Newgate with his hands bound behind him. Toller had then forced Yerman to accompany him out into the palace precinct, where they had been joined by John Gebon, Toller’s predecessor as under sheriff, and five or six other men. Between them they had taken Yerman as far as the Savoy, where one of the officials of the duchy of Lancaster liberty had affirmed his arrest. Yerman’s assailants had then ordered him to break the seals on the summons of the green wax, which he refused to do. On this, they had taken Yerman to the counter, and placed him in iron fetters over night. On the following morning, they had taken him to an inn called The Castle in Fleet Street, where they were joined by Fraunceys with the summons of the green wax, and, threatening him with imprisonment in Newgate, chained in as much iron as he might be able to bear, they had forced Yerman to break the seals of two of the summonses, thereby invalidating them. Fraunceys had grown impatient, and had demonstrated how the seals might be pulled off their documents, at which Toller and the others evidently decided that they had no more use for their prisoner and set him free. The barons of the Exchequer took a dim view of Yerman’s apparent complicity in the destruction of the official records, and placed him in the Fleet. When Toller and Gebon for their part appeared before them, they claimed that they had arrested Yerman so that he might answer a suit for debt in Toller’s name in the London sheriff’s court. The outcome of the matter is not known, although Yerman was evidently dismissed as clerk of the estreats as a result of the affair. He is not heard of thereafter.
