Watch List notes:

G William IV, half sovereign, 1836, obverse struck from sixpence die in error, bare head r., rev. crowned shield of arms (S.3832), certified and graded by NGC as Mint State 62
Sharply struck on the king's portrait with a boldly detailed shield, a beautiful example of this very rare error, and only three other examples graded MS62 or higher by NGC or PCGS. (£10000-15000)