1892 Sydney Pattern Half Sovereign
Half sovereigns were struck sporadically in Australia in the 1880s and 1890s - both the Sydney Mint and Melbourne Mint struck them in various years but more often than not, no half sovereigns were struck, with the exception of some patterns.
A number of patterns are missing from the Museum Victoria Collection: patterns were struck in most years in the absence of circulating coins but presumably they were for well-connected collectors rather than in a more official capacity. The 1892S half sovereign is one such coin: there is no mention of it in 1980 (p55, Skinner, Renniks Australian Coin and Banknote Catalogue, 1980) or 1989 (p25, Skinner, Renniks Australian Coin and Banknote Values, 1989) but a proof with unknown mintage is listed in 1985 (p52, Skinner, Renniks Australian Coins and Decimal Banknotes, 1985). It is unclear if this is in error but it has gone on to become "Unconfirmed pattern" (p52, McDonald, 2014 Pocket Guide to Australian Coins and Banknotes, 2013).