I made photos of the pages on "The Mounted Bren" from
The Bren Gun Saga by Dugelby
for research purposes.
No mention is made of the manufacturing of these in Canada. Despite the fact that this book is highly sought after (
wow!), the information in this chapter certainly doesn't seem to be the final say on this topic. It doesn't differentiate very well between the various types of mounts that were made. Here's hoping someone can add to this.