Watch List notes:

BRITISH COINS, MILLED GOLD SOVEREIGNS, Elizabeth II, Gold Proof Sovereign, 2007, frosted design elements, with bullion type Gold Sovereign, 2007, fourth crowned portrait right, engraved by Ian Rank Broadley, IRB raised below head, finely toothed border within twin linear concentric circles and raised rim both sides, rev re-engraved St George slaying dragon with sword, extra fold in cape to previous reverses, longer helmet streamer with different strand arrangement, horse with longer fuller tail nearly touching lance, flatter shallower design with less sinew detail to bodies of St George, horse and dragon, longer thicker broken lance on left side of ground-line, more definition to ground, dragon tail with extra curl onto ground, dragon with very curved claws, extra claw on lower arm, date in deeper exergue, very tiny BP doubled and touching ground above without stops (Bentley -; S 4430). Both practically as struck, the differences in the design not noted in the Standard Catalogue, without boxes or certificates. (2)
Edition limited to Proof=12,500, the 2007 production figure issued is no longer published for bullion type, but the edition limit was 75,000
This different reverse appears to be of cruder workmanship to previous years with its "shallow" appearance to the main elements, but has more detail in more minor elements of the ground and lance. Perhaps in years to come this will be delineated separately in the standard catalogues as a one year only type.

Estimate: £350-400