"Ontario, Canada, Marriages, 1826-1936," database and images, Ancestry, (www.ancestry.com: accessed 8 April 2018), Marriage of William H Lethbridge to Annie McPhail, 20 January 1886, St. Thomas, Elgin, Ontario, "Registrations of Marriages, 1869-1928," Archives of Ontario; Toronto, Ontario, Canada.
"Ontario Deaths, 1869-1937 and Overseas Deaths, 1939-1947," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:JNXV-DZD : 10 March 2018), William H. Lethbridge, 22 Apr 1897; citing Southwold, Elgin, Ontario, P143 CN007695, Archives of Ontario, Toronto; FHL microfilm 1,853,835.
It may be possible to confirm family relationships with William by comparing test results with other carriers of his Y-chromosome or his mother's mitochondrial DNA.
However, there are no known yDNA or mtDNA test-takers in his direct paternal or maternal line.
It is likely that these autosomal DNA test-takers will share DNA with William: