I'd look in Wood Green Middlesex, England. According to his find A Grave memorial # 91461810 that's where he was born.
All census records I have seen for William Humphrey show that he was born in Virginia.
"History of the Upper Ohio Valley" Vol. II, 1890.
Presented by Linda Fluharty from hard copies provided
by Mary Staley & Phyllis Slater.
It says he is of English descent, but not that he was born in England.
Find-A-Grave owner is non-responsive on providing any proof of birth in England.
My research also shows additional children.
No luck on parents for my 3rd Great-Grandfather.
I am willing to share any info on his 21 children.