This must be Alexander Campbell, son of Duncan Campbell who are both listed in the 1914 Toronto City directory living on the north side of Heman Street, Mimico.
According to his attestation papers dated August 23, 1915 at Toronto, Alexander Campbell was born on March 8, 1893 in Glasgow, Lanarkshire, Scotland. He listed his father Duncan Campbell, Caledonian Buildings, Mount Vernon, Glasgow, Scotland as his next of kin. He was a locomotive fireman and had no previous military experience. He was 22 years and 5 months of age and stood 5 feet 9 1/2 inches tall. He had blue eyes, brown hair and a fair complexion. He had a two inch scar on his left leg. He was a Presbyterian.
His father is listed as living on Heman Street in the 1921 Toronto City directory.