William came from a Gloucester family, a probable ancestor being Roger Heyberer, parliamentary burgess in 1295 and bailiff from 1299 to 1301. His kinsman, another William Heyberer, had become chaplain of St. Mary de Crypt by 1353, and was rector there by 1357.
Heyberer’s involvement in Gloucester affairs began in 1359 and was to last until his death over 30 years later. His first appointment as bailiff in 1361 was extended for another three consecutive years, and during the whole period he twice represented the borough in the Commons (in 1361 and 1362). Similarly, he was again bailiff when returned to Parliament in 1371 and 1372. His elections in 1365, 1373 and 1377 all followed immediately upon service in the same post. It was again while bailiff that he was returned for the shire to the November Parliament of I 384 and only shortly after relinquishing office that,it October 1385, he was re-elected. Meanwhile, in July 1370, Heyberer had been one of the burgesses who assisted in an official investigation of the town’s liberties, and in January following he had acted as a juror in a matter of some, if only local, importance:the problem posed by a royal grant to the townspeople of ‘Seintmartyn-Place’ enabling them to build a clock tower, a privilege which was contested by the parson of St. Martin’s church. When, in June 1376, the ‘good men of Gloucester’ were granted pavage for one year towards the upkeep of their highways, it was stipulated that Heyberer, with John Head, should supervise repairs.
From 1375 Heyberer was regularly and frequently commissioned to perform local administrative tasks of one sort or another. Most notably he became a j.p. in the county five years later, and he is known to have regularly attended sessions at Gloucester and Chipping Sodbury.
Heyberer’s local connexions kept him busy in other ways. In 1371 he had stood bail for Walter Arnald, a chaplain imprisoned at the suit of the vicar of Lydney, and over the years he often provided securities at the Exchequer for lessees of land in the region, among them Sir John Thorpe, his fellow j.p., John Cassy (afterwards chief baron of the Exchequer), and Richard Nash, sometime knight of the shire for Herefordshire.
Heyberer participated in several religious benefactions in the course of his career. As early as 1364 he had joined in the foundation of a chantry in St. Michael’s church, Gloucester, and five years later he had helped to provide for a light to burn in the priory church of Llanthony during mass. Finally, towards the end of his life, in 1389 he joined with John Head and Sir Laurence Sebrooke (who had married Edmund Blount’s widow, Margaret Steward), in granting some of Head’s property in Maisemore to St. Peter’s abbey, Gloucester. The jurors at the inquiry then held to ascertain whether licence should be awarded said that Heyberer possessed four messuages and six shops in the town, as well as lands in the suburbs, altogether valued at 20 marks a year. Whether he still owned the property in Tewkesbury which he had bought in 1371, or that in Charlton Kings and Newenton acquired in 1375, is not revealed.
Heyberer is last known to have been alive at the time of his election to the Parliament of January 1390. One of his executors was his fellow MP on that occasion, John Banbury I, the Gloucester merchant, while another was Sir Laurence Sebrooke, who then represented the shire. In May 1391 they and the other executors, John Rusby and Richard Baret, obtained royal licence to alienate a messuage in Gloucester to St. Aldgate’s church in fulfilment of Heyberer’s will.
