The standard reference book is MG collectibles by Michael Ellman-Brown. If you are interested in memorabilia /collectibles its one of the few books on the subject, worth finding a copy. Having said this ;your badge does not appear in the book. If you look through this book the scale and variety of collectibles is staggering. So some items must/ will remain to be found. With more produced all the time. Hope this helps-maybe a little.
I designed a couple of batches of brass badges for Royal Mail. I was surprised how easy it was to produce a short run of complex designs for a modest outlay. This looks the same modern mount. Hence not being in the book mentioned. Not sure if this is a euro fixing or if our USA friends use the same.