[Docere]

I found this data looking at the 1931 census:

Canadian-born, Canadian parentage:

Ontario 49%
Manitoba 26%
Saskatchewan 24%
Alberta 20%
BC 19%

British Isles birth or parentage:

Ontario 36%
Manitoba 33%
Saskatchewan 24%
Alberta 28%
BC 50%

I didn't jot down the figures for Quebec or the Maritimes, where the vast majority of the population would have had multi-generational Canadian roots.

Also they didn't have parentage figures beyond "Canadian", "British" and "foreign."

What's striking is how British British Columbia really is. Note that at the time it actually had a smaller population than any of the Prairie provinces and since that time it along with Alberta were the provinces most impacted by internal migration.

Today whatever difference between BC and Ontario exists is extremely subtle, but I wonder if there was any difference in BC pre-1940 or if those born in BC sounded more "British" then.