http://automatedgenealogy.comyou can check the 1901/1906/1911 census at this site for free and also look at the original documents.
I had a look at the 1911 for Regina and the original does look like Willsmer, he is a clerk in a govt. office and so are J W and Percy that Sandra found. He is listed as single and lodger and the other two are listed as occupants. William and Catherine Rose are listed as head and wife.
I tried to find him on the 1906 but, if there, he is badly transcribed so it would take lots of hours of looking.
www.collectionscanada.gc.ca/databases/index-e.htmlyou can look at passenger lists (originals) but you need the name of ship, date of arrival and port and then you need to scan all the pages looking for the surname. You do have some ships and dates so you could look at the passenger lists and see if you find something that we have missed.
If you go to the home page and use the search, you may be able to access the 1916 census but it is by district and not by surname so that can take hours of scanning pages.
The 1921 Census will be available for transcription sometime after 2013 but it will probably be many years before it will be online.
Electoral Records in Canada are not readily available. We have very strict privacy laws in this country that can make searching difficult. Lots of information for pre 1900 but not so much for after. You need to rely on local libraries and newspapers and their archives. That is why I suggest using the library. BMD's are also by province (no central registry) and most use the 100/80/50 years.
www.reginalibrary.ca"Ask a Librarian"
I would suggest contacting the Regina Public Library. They have a Prairie History Collection which could include Henderson's Directories. If he stayed in Regina for any length of time, they may have access to information that isn't online. BMD's for Saskatchewan are not easily accessible and marriages have not been transcribed for on line viewing as yet. They should have access to old newspapers, etc. that could mention your Harry.
I did check Canada 411, the online telephone directory, for Willmers and there are no listings in Canada.
Sorry that I couldn't be much help.
Sandra's friend in Canada