Regarding the silver badge , many 'one off' badges were not sent for hallmarking to save on costs as the money for the badge came from branch funds. Also , with it having a button hole fitting it may have been difficult to fit in the makers mark , 'silver' stamp
and member number ?
I think one reason for the 'brooch bar' fitting was simply ease of use , the mini basic pin fitting badges would have been difficult to pin on to clothes .
When the badge was redesigned (after a vote at the 1946 25th Anniversary Conference ) the 'new' badge was a similar style (side arms) to the old 'brooch bar' type (and the attached 'canteen' badge).
P.S. Perhaps the mods could move this thread to the British (rather than Canadian) section ?
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