The records have little to say about William Bettenham. He was presumably a relation — perhaps a brother — of Stephen Bettenham (d.1415) of Cranbrook, with whom he was sometimes associated. Yet while Stephen’s successful legal practice enabled him to acquire landed holdings in Kent estimated as worth more than £100 a year,
Further references to Bettenham offer little help in providing an explanation as to why he was twice elected knight of the shire. On occasion he acted as a feoffee of property for his neighbours — as he did in 1380 on behalf of John Monyn of Dover — and it may be speculated that he had some sort of training in the law, for those employed as commissioners of gaol delivery were often qualified in this way. In November 1385 he had dealings with Sir Richard Stury, knight of the King’s chamber, with whom he entered into recognizances for 100 marks; but nothing has been discovered about the background either to this transaction or to a similar one of two years later, which entailed his being bound to Thomas Hartridge and Henry Perot in the sum of 1,000 marks. It was in association with Stephen, his presumed kinsman, that he stood surety in 1394 for the good behaviour of another Kentish man. Three years later Bettenham and his wife successfully petitioned Pope Boniface IX for permission to have their own portable altar.
Bettenham is not recorded alive after February 1400.