Watch List notes:

BRITISH COINS, George III, Uniface Lead Trial Striking of the reverse of a Sovereign, undated (c.1816-1817), engraved by Benedetto Pistrucci, St George, helmeted with thick streamer and cloak, slaying dragon right with broken lance, left forearm visible gripping rein as early gold trial piece, broken lance on groundline with BP below, 24.5-25mm flan of ovoid shape, 1.67g (cf Bentley 935). As struck but with patchy spots and tone, good extremely fine and of the highest rarity.
The gold version of this design in the Bentley Collection sold for £11,040 including buyer's premium

Estimate: £600-800