Sir John Pelham, knight of the Bath, Sheriff of Sussex and Surrey had a birth date after his parent's (Sir Walter de Pelham) death date.
We know that Sir John Pelham, knight of the Bath, Sheriff of Sussex and Surrey died in 1429 - making his earliest birthdate 1329,
so either these unsupported dates 1239 - 1292 for Sir Walter de Pelham are wrong, or John isn't his son.
According to this
https://www.historyofparliamentonline.org/volume/1386-1421/member/p...
he was the son of Thomas de Pelham, Il, of Warbleton and Agnes de Gensing.
We're pretty sure the Sir John Knight existed.. See https://www.geni.com/discussions/221390?msg=1428711