Two historical records claim a direct line of father-son descent from Ivo to Eldred to Ketel to Gilbert, which was the name of the father of William de Lancaster (also known as "William son of Gilbert"). These were records made much later in Cockersand Abbey and St Mary's Abbey in Yorkshire. But modern commentators believe this to be impossible, and made by placing a sequence of lords into the simplest possible family tree. Furthermore, records have been found which describe Ketel not as William's grandfather, but as his uncle (Latin "avunculus", so probably a maternal uncle).