Watch List notes:

George IV (1820-1830), Pattern Sovereign struck in Barton's Metal, (1825), uniface, reverse crowned shield. (Murdoch 417, Marsh 10D R5). As struck, very few examples known. Experimental patterns struck in Barton's metal exist in most denominations usually of gold and silver dated 1825. Bartons Metal is gold electrolysed copper where a thin sheet of gold has been laid over a copper core and struck as method to show how a token coinage could be produced. The Deputy Comptroller of the mint at this time was John Barton (1771-1834) who was an engineer and responsible for inventing new more efficient machinery at the Royal Mint. Many of the new methods and machines were written up in detail in the Mechanic's Magazine, volume III – 1824 in issues 63-67. The Bartons Metal patterns of 1825 are all uniface obverse and reverse designs and are extremely rare.