I’m trying to help out someone who found this on the Thames River foreshore. All the terminology for these old buttons is much the same but I’ve not seen the lettering as shown here. Thanks!
That 2-hole brass shirt/underwear button's backmark is written in Old English Script, including lower-case letters. The latter feature is extremely unusual. The backmark says "Improved Patent".
That’s what I thought about the lettering, really weird looking and I can’t find “improved patent” in the places where I usually research. With the Thames being the origin of the find who knows? Thanks anyway.