Watch List notes:

Elizabeth II (1952-), Trial Planchet for a 50-Pence, c.1967, by Hugh Graham Conway, on a 'squircle' flan, 50 broadly spaced (4.5mm.), rev. 50 narrowly spaced (2.5mm.), 25.5mm., 11.29g, extremely fine, and presumed unique to commerce.
provenance
From the E J Thorne Collection
Estimate: £600 - £800