Bannebury emerged from obscurity to a place in the shire community of Sussex through his marriage to the elderly widow of Sir William Percy. He thus held for the remainder of his wife’s life (about nine years) the Percy estates at Truleigh and Woodmancote in Sussex, and at Wambrook in Dorset, which together gave him an annual income of at least £51, as assessed for purposes of taxation in 1412. In addition, he and his wife leased from the Benedictines of Sele priory their grange and tithes at Southwick, for which they paid a yearly rent of £10.
It was also to his marriage that Bannebury owed his association with Robert, 4th Lord Poynings, who was his wife’s fellow-executor of Percy’s will. As one of Lord Poynings’s feoffees he presented incumbents to the rectory and chantry at Poynings in 1411, and when, in July 1419, he and Ralph Rademylde acquired a lease at the Exchequer of the important St. Cler estates during the minority of the heir, it was Poynings who offered sureties on their behalf. Bannebury is not known either to have been appointed to royal commissions or to have served in a military capacity overseas, although he did make a loan of £9 10s.8d. to the Crown in 1417, perhaps as a contribution towards Henry V’s second expedition to France. Bannebury’s wife died within three months of the dissolution of his only Parliament in November 1419, and following his consequent loss of the Percy estates he was not elected to represent Sussex again.