Chris, Thanks for your message. Since I posted my original I have discovered and joined The Witheridge Family History society. You might like to pay the website a visit - and/or join - certainly your research and family history would be welcomed and you might find some links, I did!
You don't give a name or dates for the ancestor of yours with the Wetheridge/Witheridge connection - mine were based around Bideford. Mine are: William Witheridge born 1799 in North Tawton Married 11 April 1824 to Fanny Cawsey in Northam, Bideford William died 1870 in Bideford.
William's father was John Witheridge born abt 1760 in Bideford, married in North Tawton in 1798 to Mary Atkins