William is said to have been born 'about the end of the 14th c.'[1] and that he was knighted by Robert III who died in 1406. That he would have to have been of full age to be knighted is unclear and that he could have been as young as 14 when he could marry and witness documents is also unclear. It would be fair to consider that he was at least 16 and one can infer he was born before 1388.
Sources
↑ 1.01.11.21.3Burke, John Bernard, "A Genealogical and Heraldic History of the Landed Gentry of Great Britain and Ireland", London: Henry Colburn Publishers,1879, Ed. 6 Vol. II, Archive.org,
p. 1138
↑Nisbet, Alexander, "System of Heraldry, Speculative and Practical", Edinburgh: William Blackwood, 1816, Vol. III, Archive.org,
p. 258
↑Morehead, John Motley, "The Morehead Family of North Carolina and Virginia", New York: private, 1921, Archive.org,
p. 6