Sometime between the 1901 census and 1906, Angus Noble and family took over the boarding house at 5 Simpson St.
1901 census, Angus, Annie, sons John and William and Margaret Cameron/Cant/Noble are at 18 Harbour St.
07 Dec 1906 The newspaper Inverness Courier has an article on Angus Noble, 5 Simpson St, found guilty of beating his wife about the head and body, and breach of peace.
28 May 1907 Maggie Noble has a baby girl, Maggie Ann, at 5 Simpson St.
20 August 1907 The Aberdeen Press and Journal runs the sad story of baby Maggie Ann (see post 142 for article) which occurred at 5 Simpson St.
10 Sept 1907 Baby Maggie Ann dies at 5 Simpson St. Cause of death "convulsions?" The question mark is theirs, not mine. Mother Maggie Noble, informant, was not present; she was at Inchyettle, Cawdor at the time.
03 Jul 1908 Angus Noble of 5 Simpson St dies in hospital. Cause of death: cirrhosis of liver and uncertain. Son William of 5 Simpson St is informant.
Feb 1909 Maggie Noble sails to Canada, destination Toronto, with a corresponding border crossing attempt in Nov 1909 which indicates a brother "Joseph" (which should be John) at 5 Simpson St. Nairn.
1911 Scottish census Widowed Ann Noble, lodging house keeper, with son William and several boarders at 5 Simpson St.
1920 Death of Ann Noble at 5 Simpson St. Cause of death, hemiplegia 4 yrs. Signed by J. Noble (absent).
I think if you accept the fact that the Nobles are the ones raising Margaret Cant/Cameron, that she is indeed the mother of Maggie Ann as well as Victoria in Toronto. And remember, Ann Noble's mother was a Cameron!