According to his attestation papers dated August 4, 1915 at Toronto, William Johnston, Church Street, Mimico was born on July 27, 1897 at Ruthenglen (?), Scotland. He listed his mother, Mrs. Warden Johnston as his next of kin. He father also enlisted the same day just before him. He was a machinst by trade and had no previous military experience. He was 18 years of age and stood 5 feet 6 inches tall. He had grey eyes, a fair complexion and brown hair.
According to his family both he and his father Warden Johnston, participated in the battle of Vimy Ridge and were wounded.