I think this is one where you may have to resign yourself to not being able to solve.

The research I did on the family didn't suggest any of them came from Wales.
It's possible that Oliver got muddled up as he would have been nearly 70 when he wrote the letter in 1943. Perhaps he heard the welsh place but it was in connection with someone else and not his father. What he actually heard is now lost in the mists of time.