Just a thought! When researching have you ever considered looking at the civil registration indexes with variant spellings?
I have the name McKiernan/McKernan, twice in my line, one of whom was from Drumkeeran, the other from another county. In my research over the years, I have found people with various spellings, with and without the Mc. If you would like to check this out, there are indexes on the web. Check out this website via a search for Wickham & McKiernan. On this site there is a listing for the name without the Mc. Personally, I researched the spelling of McKernan and have listings of the indexes for births, marriages and deaths to about 1905.
My line in Drumkeeran starts with Bryan, born in the early 1800s. It also has the names, John, James, and Hugh.