Identifying A Mystery UK Coin

I found a curious coin in a "junk tray" at my local shop here in Canada.

It has a very similar size and weight to a copper one cent coin (~19 mm and ~3 g) but is a little thinner.

There is a young Victoria obverse with a date below. The pictures don't show it, but my best guess at the date is 1872.

The reverse looks like a halfcrown or sovereign, where a wreath encloses a crowned sheid.

But the size is much smaller than a halfcrown, and the metal is nothing like gold. It is superficially most like a sixpence, but no sixpence type matches with either this reverse or obverse.

Here are the pictures.







My initial guess: the remnants of some kind of counterfeit half sovereign

Any advice would be very appreciated! Thanks for looking!