I live on Starbuck Street, Rudry, Caerphilly. It seems the land was owned by Edward Starbuck Williams around 1880s. Also his wife was Margaret Rowland Williams. Interestingly the next village from here is called Waterloo - maybe he also owned land there and name came from Waterloo street in Swansea?
This sounds very much like he's a part of the Williams family who built Scorrier House and own Caerhays Castle & much of the south coast (between St Austell & Truro) of Cornwall? Made their money in mining (and owned the copper smelting works in Swansea) Keen horticulturists - Caerhays Castle has beautiful camellias & magnolias - there's even one named after them ... something like "camellia williamsii". Back in the 1970's I lived at Portholland - part of the Williams estate. Everyone referred to him (some of us still do) as "Squire Williams". There are some graves in Caerhays churchyard, but most are 1900's (I've attached the oldest/clearest). They're on FindAGrave, under "St Michael Churchyard, Caerhays". Jane Edit: Just to clarify - I took the photo and put it on FAG, so there's no "copyright" problem.
I don't believe my Williamses are the same family as the one at Caerhays. I found detailed information about the Caerhays one, and there are no names or dates to link them to mine, although my family were involved in the copper trade, mainly as assayers. Code: https://en.m.wikipedia.org/wiki/Williams_family_of_Caerhays,_Burncoose_and_Scorrier