George VI 1952 proof Penny PF64RB, the only example that exists

George VI (1936-52), Proof Penny, 1952, second issue (1949-52), bare head in profile left, raised HP below, initials of designer Thomas Humphrey Paget, legend commences lower left with toothed border surrounding, GEORGIVS VI D: G: BR: OMN: REX FIDEI DEF:, rev. struck en medaille, Britannia seated right with heraldic shield and trident, crested waves below, sea beyond each side with lighthouse at left, date in exergue, denomination as legend surrounding with toothed border, ONE PENNY, weight 9.52g (Peck - reverse B; Fr. - dies 3+C; S.4117). Attractively toned with full underlying brilliance and lustre, one darker patch of tone at X of obverse legend, small spot below truncation, one tone spot on reverse field under last N of legend, otherwise as struck and the only example known to exist, has been slabbed and graded by NGC as PF64RB, Unique!