Coming from an old Rochester family with a long parliamentary pedigree, John was a kinsman, possibly the son, of William Gillingham, who had represented the city in the Parliament of 1391. His putative grandfather, another William Gillingham†, had done so four times between 1377 and 1388, while another probable ancestor, Thomas Gillingham, had not only sat for Rochester twice but had also been knight of the shire for Kent in 1346.
Gillingham probably made his living through the traffic that passed through Rochester on its way to the Channel ports or on pilgrimage to Canterbury. His interest in the George atte Hope, almost certainly an inn, indicates his occupation as an ostler, the description given him when in Michaelmas term 1433, while he was a sitting MP, he was twice sued in the court of common pleas for debt. He failed to appear to answer one of the charges and when the sheriff of Kent was ordered to attach him, he was not to be found in that county, perhaps because he was attending Parliament at Westminster.
Gillingham died shortly after the Parliament was dissolved. He was dead by 26 Apr. 1434, when his widow, Joan, borrowed money as a woman sole.
