Great Britain 1808 Ireland MERMAID Free Frank Stampless Folded Cover Drogheda

1808, folded cover, postmarked with red DROGHEDA 24 straight-line, to the Honourable John Foster, Chancellor of the Exchequer (Ireland), Dublin, with red crowned "FREE" double-framed "Mermaid" datestamp (Sep 30), manuscript"8" charge fee applied in error and cancelled upon arrival in Dublin, light vertical filing fold, a fine example of this scarce and desirable "Mermaid" marking.