Perhaps a lawyer, Poleyn was probably a native of Worcestershire if not of Worcester itself. While his early years are difficult to trace, it appears that he was the William Poleyn who married Iseult Solers, the daughter and heir of a minor west-country gentleman. At the beginning of 1398, when she was 13 years old, she was in the service of the prominent Herefordshire esquire, Thomas Walwyn† of Much Marcle, but she had become Poleyn’s wife by the autumn of 1404. In October that year the couple conveyed her inheritance at Lower Bullinghope in Herefordshire to a group of feoffees, without having obtained a royal licence to alienate lands held in chief. The escheator of Herefordshire therefore seized the estate on behalf of the King, who in the following summer pardoned the feoffees for their part in the unlicensed conveyance.
It is likely that Poleyn was a retainer of Richard Beauchamp, earl of Warwick, since an auditor of Beauchamp’s of that name resided in Iseult’s home county of Herefordshire in the latter stages of Henry V’s reign. In 1419-20 this official travelled through the West Country, Midlands, East Anglia and South Wales on his master’s business, and in the following year he spent three weeks at Berkeley castle auditing the accounts of other Beauchamp officials, among them the earl’s receiver-general. During 1420-1 he also visited London on three occasions, toured Gloucestershire, Warwickshire, Wiltshire and South Wales and examined documents relating to the Berkeley inheritance, of which the castle was part. It is nevertheless possible that he left Beauchamp’s service under a cloud soon afterwards, having incurred the blame for financial losses suffered by the earl in 1423.
The fact that the MP was a feoffee for Richard Oldcastle and Elizabeth his wife by the latter stages of Henry V’s reign supports the suggestion that he and Beauchamp’s auditor were one and the same man, since Elizabeth was previously the wife of the former Beauchamp retainer, Richard Ruyhale† (d.1408). In June 1420 Poleyn, described as ‘litteratus’, helped to present a new incumbent to the parish church of Birtsmorton, Worcestershire, a Ruyhale family living. It was likewise as a feoffee that Poleyn was involved in the disposition of the Ruyhale estates, including the manors of Birtsmorton and Queenhill in Worcestershire and Dymock in Gloucestershire, both before and after Elizabeth’s death in 1428.
In the following year Poleyn participated in the elections to the Parliament of 1429. His name appears in the combined return for Worcester and Worcestershire, and it is likely that he witnessed the election of the county’s knights of the shire as well as that of the burgesses of Worcester.
Some two years after leaving the Commons, Poleyn put his name to a covenant between the commonalty of Worcester and the local cathedral priory. Through this agreement, intended to improve the priory’s water supply, the citizens licensed the monks to pipe water along the city’s ditches and under its walls to their house, in return for a nominal annual rent of a rose.
