I think I have cousin James Louden b. about 1776 in Dunde, Angus. Married Mary Adam 1801, and had children James (1801), Jean/Janet, David, Christian, Allison, John, Andrew, Thomas, William, Jean Smith (1824). Note the similarity of given names. I can trace it down, but not up. So I guess I'm stuck too.
However - there's a William who ma. on Novemver 13th, 1747 Isabel Johnston and had Alexander 3/17/1765 in Fife. That's a long time wait to produce a child, so I wouild expect they had earlier son William.
Regards - LDS films M114412 and C114538.