George III (1760-1820), Pre-1816 issues, Proof Halfpenny, 1806 (late Soho), in gilt-copper, edge centre-grained, 9.59g/12h (BMC 1362 [KH 36]; Selig 1401; S 3781). Fields lightly hairlined, dig in obverse field and small edge knock on reverse, otherwise about as struck £400-£500