There are three very good Fowell family trees going back to the Norman and Plantagenet periods. They are available for free online and can be found in "A Genealogical and Heraldic History of the Commoners of Great Britain", the "Stemmata Robertson et Durdin", and "The Visitation of the County of Devon in the Year 1620". This page summarises the three trees and discusses the points where they diverge: stirnet.com/genie/data/british/ff/fowell1.php