Interesting theory but I am not convinced that all Ratcliffes, Radcliffes or anyone else with a variant surname are descended from this one person. The surname Ratcliffe is of toponymic origin but it probably wasn't used exclusively by one particular family.Radcliffe in Lancashire would seem to be the most likely place of origin for most Ratcliffe/Radcliffe families. Certainly these two names were often mixed, even up to the end of the 19C, and similarly the other variants would have evolved because so few could read or write. I was born within a mile of Radcliffe Tower and so it would be great to prove a connection with Nicholas de Tailbois but I have my doubts. Maybe when DNA testing becomes cheaper!