I was interested to see your posting from 2003. My great uncle was also called William Ernest Maxwell. However , he served in the Indian Army and died in 1951. His father was Thomas Alexander Maxwell, 1862-1912, of Raphoe, who married Harriet Alicia McGuire, (1871-1942), who was the daughter of Sarah M Acheson. Several Achesons married several Shaws. The first writer on this topic mentioned a Shaw connection.  I have no useful information on Thomas Alexander  Maxwell's parents. He, and after his early death, his wife, ran several businesses in Belturbet. I wonder if our Maxwell lines have a common ancestor?