Watch List notes:

AU55 | Charles II (1660-85), silver trial of two reverses for a Pattern Shilling, 1676, crowned rose, thistle, harp and lis around four interlinked Cs, date at end of legend, MAG . BR . FRA . ET . HIB . REX 1676, rev. crowned rose, thistle, harp and lis around four interlinked Cs, date either side of crown, 16-76 MAG . BR . FRA . ET . HIB . REX., edge plain, weight 8.46g (Peck 489 EXR; Bull 565 R5). Toned, has been graded by NGC as AU55, extremely rare.

NGC Certification 6321659-005

These unusual patterns are in the Miscellaneous section of Peck where he concludes they are more likely to be trials for shillings than a copper coinage.
Estimate: £4,000-6,000