Watch List notes:

WINDSOR. George V. 1910-1936. Proof AR Crown. Dated 1928. Bull 3634 (R5); ESC 368A; SCBC 4036. Exceptionally well struck with considerable brilliance in fields. In NGC encapsulation 6473207-009, graded MS 64+, though in our opinion a very rare proof striking.

From the Gainsborough Collection. Ex Spink 168 (15 April 2004), lot 300 (there in PCGS encapsulation graded PR64).