Watch List notes:

MINT ERROR ~ AU58 BN | Elizabeth II (1952-), Double-Reverse Mule Penny, 1964, struck with two reverse, edge plain, 12h (cf. Spink 4157), a remarkable Modern error or more probably 'Mint Sport' piece, patinated, nearly extremely fine, extremely rare, in NGC holder, graded MINT ERROR ~ AU58 BN (Cert. #6135255-022).

Estimate: £400 - £600