Watch List notes:

George VI (1936-52), Pattern for a Halfcrown, 1937, in silver, a model striking of the approved reverse design by Kruger Gray, edge milled, 13.99g (cf. S.4079), the surfaces lightly brushed to produce matte surfaces, otherwise much as issued, of the highest rarity.
Undoubtedly from the Kruger Gray collection, largely dispersed by Spink through the Numismatic Circular in July-August 1978, although this piece not listed.
, , A reverse model Sixpence of the same series was offered in the United States in August 2013 and attained $1,300 (~£800)
Estimate: £800 - £1,000