Diana
My research matches yours !!. Really good to know there is a link. We are not alone though as I have had contact previously from a descendant of John Whitney (b 1791).
David (1811) and his wife Louisa are buried (along with their son George) at St Mary's Church Rogiett. This church sits alongside the main South Wales to London railway line just after Severn Tunnel junction - and I can't tell you how many times I've looked at the church as I've sped by on the train without realising my Gt Gt Grandparents were buried there. Unfortunately the graves are not marked.
It appears that my branch moved increasingly west ward, moving from agricultural occupations
and into coal mining in the Monmouthshire and Glamorganshire Valleys. If you have time to explore the Whitney resource there is a photo of my Grandparents posted.
I am no further back than you - having stalled with David. Looks like I need to do some research in the Hereford record Office.
Best wishes
Rob