Watch List notes:

WINDSOR. Elizabeth II. 1952-present. NI Trial Die Strike (25mm, 4.22 g, 12h). London mint. Dated 1957. ROYAL MINT ~ TRIAL DIE ~, hexagram; 1957 (date) in center / ROYAL MINT ~ TRIAL DIE ~, hexagram; 1957 (date) in center. Cf. DNW 102, lot 2767 (for type). Spot. As made. Cancellation crimping to edge. Rare with double reverse.

These 1957 Royal Mint trial strikes were reportedly found by metal detectorists in spoil heaps in Dagenham, East London where the remains of the Royal Mint building on Tower hill were taken after demolition.