1888 Melbourne Pattern Half Sovereign
No circulating half sovereigns were struck anywhere in the British empire in 1888 and very few were struck in 1889. It is believed that their low durability and high production cost prompted the introduction of the double florin as a substitute (p48, Rodgers, Britain's Enigmatic Double Florin in Coin News, July 2020). This explains why the Royal Mint in London produced no half sovereigns in 1888 or 1889. In 1889 half sovereigns were struck for circulation at the Sydney Mint and patterns were struck at the Melbourne Mint: presumably the double florin did not make it to Australia in great numbers, and local demand necessitated a small issue of half sovereigns in 1889. The Melbourne Mint struck perhaps two pattern 1888 half sovereigns.
Early Rennicks catalogues also make mention of the 1888M pattern half sovereign: in 1980 it was listed with the note "Only Pattern Proofs known to exist" (p52, Skinner, Renniks Australian Coin and Banknote Catalogue, 1980) as well as in the list of pattern half sovereigns produced by the Melbourne Mint (p55, Skinner, Renniks Australian Coin and Banknote Catalogue, 1980). In 1985 it was listed as proof only with an unknown mintage (p52, Skinner, Renniks Australian Coins and Decimal Banknotes, 1985). In 1989 it was stated that an example was sold for $9,000 in the Spink Australia November 1981 auction but no other details are given (p25, Skinner, Renniks Australian Coin and Banknote Values, 1989).
Two examples were sold as parts of lots 628 and 629 in Sotheby's auction of the Murdoch collection on 21st July 1903. An example was listed and photographed as lot 1004 in a Spink Australia in November 1981.
In more recent times it has been listed as being of the "Normal IEB" obverse type (p52, McDonald, 2014 Pocket Guide to Australian Coins and Banknotes, 2013) suggesting a recent sighting.