I happen to have a really old p90 - like from the 1940s! but it has no base plate.
I got an older plate from the eeb, but it's weird.
 
 
First off - the side ears are not folded, the plate is totally flat, and second the actual holes have a little bit of tin or something reinforcing them. Anybody seen this before?
the base metal is brass, with a bit of chrome.
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