Canada CL13

1926 (July 7) Red Lake - Sioux Lookout First Flight; A.J. Algate The Map Specialty advertising envelope with flight cachet in green, bearing 1c orange, Die II and 2c green Admiral stamps tied by light grids, Red Lake split ring at left; on reverse (25c) Patricia Airways, Style One trial colour proof on Canary coloured paper (very distinctive from the issued yellow paper) with route inscription in green, tied by same Red Lake split ring on departure and same-day Sioux Lookout CDS on arrival. A striking and one-of-a-kind Style One coloured proof on cover, VF (AAMC CL13 trial colour - 2602a; Unitrade CL13 trial colour)

Only one other Canary paper trial colour proof is known used on flight cover; but instead shows the official blue-black route inscription.