I think John is quite right to place an emphasis on primary sources, and
encouraging some caution in relation to published research by others.
Although I use Ancestry regularly I would never rely on the Millennium File
information or other people's research (published or not) and have found
that members of my own family have been grafted onto other family trees
etc. Sadly there are lots of public trees which repeat these errors, but
that doesn't make them accurate.
My husband's family name is now relatively unusual and there is a huge body
of work including published genealogies in the US which I know because of
my own research and his local knowledge to be completely unreliable.
Pre-19th century it seems to have been a very common surname in that
locality (Essex/Suffolk) and across all classes. Most males had one of a
handful of given names and being named after a prominent landowner or MP
wasn't rare. Most of us on the Powys list probably have a
Powell/Powel/Hywel/Howell/ap Hywel ancestor somewhere, most of them
unrelated and from humble origins.
Good luck with your research/Pob lwc gyda'ch ymchwil
Sara