Newfoundland 1929 3c on 6c slate error, SG188aNewfoundland 1929 (23 Aug) 3c on 6c slate, type 101 surcharge in red, ERROR SURCHARGE INVERTED, in a very rare block of 4, SG188a. A brilliant quality mint block with original gum (lower pair are unmounted mint). A very rare inverted surcharge error as only 75 examples originally existed and very few exist which have never been hinged. The stamp was printed by De La Rue featuring the Upper Steadies, Humber River. Accompanied with a British Philatelic