I have seen hundreds of ex-Cdn service Chinese marked magwells. These are directly out of Cdn service. Not one of them was scrubbed or altered in any way. I have seen the Chinese script scrubbed on dewats, and I think that was to make them more saleable as many guys did not want the foreign script. However these days, they seem to be as popular as the non-CH script magwells.
Any of the knurled cocking handles that I have seen that were Cdn had the C/l\ stamped on them facing outwards on the washer like portion. When a gun was altered, there was an X stamped on the end housing cap. Of the thousand or so ex-Cdn cut up stens I have seen, the tubes were all modified for the push thru cocking handles.
Your barrel will be British, and as others have said, possibly a recycled mk1 or mk3 barrel. There is apparently a difference in diameter between the ends of the two.
If you show the back half of the tube, with the trigger area, it may be that your tube is British as well. Your sten may be a mixmaster of parts and pieces.
Apex gun parts got a bunch of original bayonets a few years ago, and have varying manufacturing marks. They weren't charging much for them at first, but as the demand went up, so did the prices. They still have some remaining. I think they may have come out of the Irish military stocks....they really seemed to have a time capsule with a lot of odd equipment like 25 pounders and Boys rifles. There were reproductions a decade or two back with the BJ&S marking on them. It was always said back then that you only paid what you would pay for a repro sten bayonet, as it was hard to differentiate them from the real thing.