>>Out of curiousity, did the Canadians equate an inch to 26.5mm? Seeing
>>as how it isn't that, I mean?
>
>No, I don't know why the British standard was called that. Maybe it's
>a one-inch bore but the cartridge is slightly larger?

The British, (and thus the Canadians through to about WWII), sometimes use slightly incorrect bore sizes to distinguish between things that are the same size but not compatible.

For example, the 76mm, 3" and 77mm were all actually 76.2mm.

I'm not sure if that's what's happening here, but it is a possibility.