Watch List notes:

COINS, EUROPEAN TERRITORIES, ISLE OF MAN George III (1760-1820), Gilt-copper Proof Penny, 1798, Soho mint, laureate head right, rev Triune (Pr 18B; S 7415; KM 11). Very lightly brushed surfaces, almost mint state.
ex Dr R Caine collection of the Isle of Man, Spink Auction 145, 14 July 2000, 2740

Estimate: £400-600