Canada CL13i

1926 (July 1) (25c) Patricia Airways, Style One, green route inscription, an outstanding mint example with sheet margin at right, clearly displaying the "RED LAKE" marginal inscription INVERTED ERROR, which is furthermore noticeably shifted horizontally (16mm) to one side; brilliant fresh colour, well centered with full original gum. A major airmail rarity of the popular Patricia Airways & Exploration Co. Ltd., Very Fine, Never Hinged  (Unitrade CL13i variety; catalogue value $6,000+)

Catalogue value is for the basic airmail stamp with inverted RED LAKE marginal inscription; no premium added for the remarkable shift.