Watch List notes:

George IV, proof halfcrown, 1826, bare head left, rev. crowned helmet over shield of arms, milled edge (S.3809; ESC.2376), certified and graded by NGC as Proof-64 Cameo, a lovely example of the coin issued in the sets of this year, rich grey toning with iridescent hues
Three others graded as Proof-64 Cameo by NGC, one graded higher.

Estimate: 1500 - 2000 GBP