There is a passenger list for William MCCARTNEY, 38, married, occupation laundry supt., returning on the Montcalm 4 April 1926 from Belfast to St. John, New Brunswick.
He was returning home to his wife, Mrs. McCartney, at 454 Rosdale Ave., Winnipeg, Manitoba. Irish contact was his brother Mr. M. McCartney Cromkill Ballymena Antrim.
William had been in Canada between the years 1906 and 1925 in Winnipeg.
Did your William have a brother with the initial M? If this is your William he might have moved to Calgary at a later date. You can browse the Henderson directories for Calgary at this site
http://www.rootsweb.ancestry.com/~abwcobit/If this tallies with family information there are two possible marriages in Winnipeg for a William McCartney.
One to Florence Beatrice Baines 12/07/1910 at Winnipeg (Groom was William John)
the other to Louise Jane Odger 10/12/1918 at Winnipeg.
http://vitalstats.gov.mb.ca/Query.phpWilliam and Florence are in Winnipeg on the 1916 census but have children
Debbie