Definitely a modern pressure cast copy. Avoid it like the plague! Weight is no guarantee - the alloy used is pretty much the same density as silver and so the weight is likely to be in the "right" vicinity...
“It looks very iffy”
I’m afraid I would agree. This series is rife with forgeries, I think they were pressure cast, and poor mould fill could give this appearance. Also the absent tooth above the T of BRITT. Yes, what is the weight?
Jerry
They are much cheaper direct from China.
https://www.aliexpress.com/item/33037661091.html?spm=a2g0o.productlist.0.0.74f4359e6fBpvU&algo_pvid=51167541-c1e6-4da6-95ee-01fb214ad011&algo_exp_id=51167541-c1e6-4da6-95ee-01fb214ad011-47&pdp_ext_f={"sku_id"%3A"67398536291"}&pdp_pi=-1%3B1.18%3B-1%3B-1%40salePrice%3BGBP%3Bsearch-mainSearch
Jerry
Just a very poor attempt at a forgery I think. Like has been said, it should not have got into the catalogue if anybody bothered to examine it properly.
Has anyone got their hands on a copy yet? I'm tempted to get one from https://spinkbooks.com/products/english-silver-coinage-since-1649-7th-edition-maurice-bull?variant=40339604963522 but is there much new in the 1816-1970 section? I don't expect so as Bull doesn't go as in-depth as Davies but the 1837 mule sixpence slipped under my radar in the 6th edition.