Watch List notes:

George IV (1820-30), Proof Halfcrown, 1821, bare head left, rev. coin alignment, crowned garnished shield, edge milled (ESC 2361 (R2) {632}; S.3807), pleasantly toned with much underlying brilliance, good extremely fine, rare.
provenance
Spink Numismatic Circular, February 1978, no. 1921 - £420 - 'Proof as issued in sets, rare, toned'
Estimate: £800.00 - £1,000.00