George III (1760-1820), Pre-1816 issues, Proof Halfpenny, 1806, in gilt-copper, edge centre-grained, 9.57g/12h (BMC 1362 [KH 36]; Selig 1401; S 3781). Faint line across centre of obverse, otherwise brilliant, virtually as struck, scarce; in original metal shells £300-£400