Hi Alex,
The eBay badge has to be separated from the badge in the article, because like every badge I've seen for sale they are always cast and have too many points of similarity with the mould below, which was made sometime in the 1980's and passed around various repro makers and that is why you can come across it in brass, silver & white metal, with blades loops and sliders.
I'd really like to see a crisply die struck example, or even a quality die cast one, but am yet to do so.
Maybe one of the Norfolk collector's who frequent the forum could weigh in with their thoughts. As I stated in post 3 I don't profess to know about what was sealed back in 1937, but I would not expect it to be poorly cast.
Neil