^ that's not entirely accurate.
Take a look at this wiki page regarding WInnipeg South:
http://en.wikipedia.org/wiki/Winnipeg_South
Alcock's support went
down 10% last election. Even with or without the "extra" votes, the loss in popular support is what cost him the election, not extra people in the voting booth.
Going back further in the election data on the page, it is obvious that Winnipeg South has a fairly close amount of support historically between the Liberals and Conservatives.
Check the results from 1953, 1962, and 1988. All within a couple hundred votes.