Thank you for the response Sarah.
From this latest information it would seem reasonable to conclude that we have a positive link between Henry and the "right" William, with Sophia, even though Henry was born almost 7 years before the eventual marriage between them.
Having reached a conclusion on William, and having referred back to the baptism records previously provided by Sarah, William looks to have been born 1/9/1809, s/o John & Ann (Luke). This would fit with William's fathers name and dob on his marriage certificate.
Finding a baptism / birth record for a John Edwards (sometime pre 1790), is this possible, do these records even go back that far???
Regards, Chris