Scottish countermark Dollar Rothesay Mills

Scotland, Merchant countermark upon Spanish Eight Reales of Ferdinand VII, 1819 IJ, Mexico City Mint, Mexico, Rothsay Cotton Works, Isle of Bute, 1820, Four Shillings and Sixpence, "4/6" value with date with stop curving below at centre, robed circles and legend surrounding, ROTHSAY COTTON WORKS., rev. small punch privy security mark below reverse shield, weight 28.42g (Manville 92 this coin listed; Brunk 53815). Toned with a couple of flan flaws on host coin, almost very fine, the countermark good very fine, rare, Manville only records four pieces of the 1819 host coin date.