lilybell, I'm afraid that you will - literally - make anneelaine's head spin! Her reading/vision problem does just that.
I'm very sure she really has no idea how Charles and Annie, Gladys's parents met. I'm pretty sure that at this point she has told us everything she knows -- unless she can tell us exactly where Gladys's mother Annie and her mother were living at the time.
Gladys herself grew up with her grandmother, not her mother, apparently, and only found out who her parents were when she came of age.
We should keep in mind that Charles himself was from Burnley, just a few miles north of Manchester, and even closer to Prestwich which is on the northern outskirts of Manchester (if my guess is right about where Gladys was born).
There were Staveleys in Manchester at the time. He could have been stationed anywhere, and just in the area visiting family while on leave.
I would focus on locating close family in Canada, at this point, to see whether there is anyone who has actual memory of the Charles there.
It may be that the person who posted at Genforum and the person who owns the Staveley genealogy website (who could be the same person) would have some leads for that -- or there are the addresses in the phone book.
The problem is that there was a separate lot of Staveleys in Quebec, from Leicestershire, who were there much earlier -- around 1840 it seems -- and it's just as likely that any Staveleys in Quebec today are theirs:
http://www.staveley-genealogy.com/quebec.htmAlso, in the 1970s, there was an exodus of young English speakers from Quebec, so recent generations could be anywhere (mot likely Ontario or the West). And there were earlier Staveleys also in Saskatchewan and British Columbia ...
All that could be done is to contact Staveleys and ask whether they are descended from the family who arrived in 1912, or know anyone who is.