Henry III (1216-1272) gold Penny of 20 Pence ND (c. 1257) MS63 NGC, London mint, Willem (likely William of Gloucester [William Fitz Otto], the King's goldsmith) as moneyer, Fr-80 (7 known), S-1375, N-1000 (ER), Schneider-1, Ruding, Annals of the coinage of Great Britain and its dependencies, 3rd ed. (1840), Vol II, pg. 378, Supplementary Plate VI, 18, n. 4 (this coin cited), Evans, "The First Gold Coins of England", Plate XI, 4 (this coin), Lawrence, "The Long Cross coinage of Henry III and Edward I" (British Numismatic Journal 9, 1912, pp. 145-79), Type II. 21mm. 2.95gm. h | eNRIC' | ReX : I-I-I' | :, bearded and crowned king enthroned facing, lis-tipped scepter in right hand, globus cruciger in left / WILL | eM : O | N LVn | DeN (quatrefoil), voided long cross with rose and three pellets in each angle (second N in London lombardic). Beautifully struck and wholly original, this spectacular piece exhibits stunning cabinet tone over lustrous surfaces leading out to traces of upset rims. The centering is careful and the flan, although not overly broad, is near fully round and bears no cracks or obvious flaws.
The description of the legends got messed up, but I noticed the king's name is spelled heNRIC' ... That last symbol looks like what we call an apostrophe, but in a thread hosted by @spence, we learned that it actually is a printer's shorthand for the letters "US" which would complete Henry's latin name, Henricus.