Watch List notes:

British Coins, William IV, sovereign, 1831, without stops 1st bust, rev. crowned garnished shield of arms (S.3829A), certified and graded by PCGS as MS64+, having tiny abrasions in the soft gold on obverse but a well-detailed portrait, while the reverse is fully struck and superb, thus one of the finest quality sovereigns of this reign available on the world market
Certainly one of the finest known and as such exceedingly rare.
Estimate: 6000-8000 GBP