Watch List notes:

Elizabeth II (1952-), Trial Planchet for a 50-Pence, c.1967, by Hugh Graham Conway, on a dodecagonal flan, 50 spaced 1mm. apart, rev. 50 spaced 1mm. apart, 29.0mm., 13.20g, extremely fine, and presumed unique to commerce.
provenance
From the E J Thorne Collection
Estimate: £600 - £800