Among the more obscure men to represent Liskeard in the Commons in Henry VI’s reign, Kingdon came from a family resident in the parish of Quethiock to the immediate east of the borough. He was a younger son of Roger Kingdon, a highly prolific local gentleman who was regularly empaneled on local juries in the reign of Henry VI, attested the Cornish shire elections of 1442, and may occasionally be found as a witness to the property transactions of his neighbours, such as the prominent Stephen Bodulgate.
Although the family’s residence in the immediate vicinity of Liskeard was probably thought sufficient to qualify William in terms of the statutory requirement for residence in his constituency, it is likely that his election owed more to his family’s standing in the locality than to his own, for he is not known to have taken any part in public affairs prior to his return. Nor does his service in Parliament subsequently appear to have led to a career of office holding either locally or under the Crown, although – like his father before him – he occasionally served on local juries and attested property deeds.