S.3411 "Plume Shilling" -

James II (1685-1688), 'Plume' Shilling, 1685, laureate and draped bust left, rev. crowned cruciform shields, Welsh plume at centre, angles plain, edge obliquely milled, 5.91g, 6h (Spink 3411; ESC 763 [1069A] [R6]; Hoblyn [1877] -; Montagu [1896] -; Murdoch [1903] -; Jackson-Kent [1965] -; Hamilton [1979] -; Manville [1980] 104; Pegg [1980] -; Norweb -; Hughes [1999] 238 same dies), a magnificent example of this unparalleled 'King of the Rarities' within the English Milled Shilling series eclipsing even the celebrated 'Dorrien Magens', toned, almost extremely fine with a touch of adjustment on drapery, unquestionably the finest of only four known since 1951. 

Images courtesy of Spink.  Coin features in auction 367 - The NYINC Numismatic Collector's Series Sale, London, Jan 17, 2021. 

Unknown to numismatics until the discovery of a pair of coins in a collection unearthed during the Second World War. The find was publicised by Albert Baldwin at the ordinary meeting of the British Numismatic Society on 28 March 1951, with one of two coins exhibited subsequently illustrated in the BNJ (pp. 358 and pl. A, no. 19). It is thought the piece illustrated is that now presented to commerce, likely having passed through the Baldwin family collection until private sale.