I have been looking into the matter, Its a bit of a curly one because our lot has been WENBAN since 9th December 1772.
I think you need to work backwards through the BDM departments as these will usually list parents and other small details. Sometimes small obscure details will give you a clue. Start with the known and go back from there. I have been at it for over 20 odd years now so Patience! is a requisite. You need to document all your little findings and piece together like a Jig Saw puzzle.
These ancestors of yours would definitely be related to the original Wenbourne/ Wenban line somehow