1837-Dated (1871) William IV Gold Proof Mule 1/2 Sovereign PCGS PR66 Cameo

KM-Unl., S-Unl., Astounding Mule-Pattern Half-Sovereign. Schneider-Unl., W&R-269 (R7), cf. Marsh-412A (for mule dated 1836). 3.99gm. Reeded edge. By William Wyon after Chantrey, reverse by Jean-Baptiste Merlen. Struck from a 6 Pence obverse die. An exceedingly and fantastically rare and somewhat enigmatic issue, brilliantly mirrored in the fields with a delicate layer of mint frost over the design elements. Awarded an R7 rating by Wilson and Rasmussen, suggesting 1-2 pieces known, the 1837 "Mule" or "Pattern" 1/2 Sovereign almost suggests a curiosity or special order specimen, perhaps specially produced at the mint for a distinguished private collector--the dies, lightly rusted here and to an even greater degree on the Douglas-Morris specimen, have been heavily polished, with Wilson and Rasmussen noting that this mule "was apparently struck in 1871". Such a situation would hardly have been unusual, as demand for Victorian-era Proof Sets is known to have led the Royal mint to strike additional coins to fill orders. Regardless, the rarity of the present offering is entirely undisputed, and of the perhaps 3 pieces known, this is one of only 2 in private hands, the third piece residing in the Ashmolean Museum. Ex. Terner Collection (Goldberg Auction 20, May 2003, Lot 300) Exceedingly RARE.