This source says he was born in 1418 and died in 1479, without providing any source for the information. However, these dates fit reasonably well with the dates of his descendants.
John was an ancestor of the Duke of Marlborough and Earl Spencer of Althorpe, Northants. He married [--?--] Warnstede.
This source estimates his birth year as 1376. However, it also says his father died in 1476 and estimates the birth year of his son William as 1480, so these dates are clearly not well thought through (or they are subject to typos).
