1924 (25c) Green Laurentide Air Service Limited Semi Official Second Issue, a mint never hinged single, small green offsets on gum, still fresh and very fine. (Image)

Unitrade $ 240

Patricia Airways and Exploration Co. Ltd. Trial Colour Proof, a mint never hinged (hinged in margin only) sheet margin single from bottom right (with small "TO"), perforated 12 on canary yellow paper, otherwise same as issued stamp, very fine and accompanied by a 2018 Greene Foundation certificate. Unlisted in Unitrade. (Image)

Est $ 200

1926 (10c) Patricia Airways Semi-Official with Inverted Type A Overprint in Red, a mint never hinged (hinged in margin only) single from upper left corner of pane, with plate 2 (etc) inscriptions in margin and showing a complete inverted overprint, plus small part of a second one at right. A striking example of this rare and under-valued variety, as only two panes (16 stamps) are known to have had an inverted overprint. Accompanied by a 2015 Philatelic Foundation certificate giving it a grade of "VF 80". (Image)

Unitrade $ 750

1926-27 10c Patricia Airways and Exploration Co. Ltd. with Type A Double Overprint in Red, One Inverted, a mint hinged single, with bright, fresh colour, very fine. A striking error not often encountered, as only two sheets (16 stamps) were printed. Accompanied by a 2010 Greene Foundation certificate. (Image)

Unitrade $ 1,000

1926 5c Patricia Airways and Exploration Semi-Official with Type B Overprint, mint never hinged bottom margin single, with Type B overprint in black, quite fresh and very fine. (Image)

Unitrade $ 412

1926 (5c) Patricia Airways and Exploration Semi-Official Issue with Descending Type D Overprint, mint hinged, very fine. Most of the 200 overprinted stamps were done in an ascending direction, thus descending being quite scarce and under-valued. (Image)

Unitrade $ 1,500

1926 10c Patricia Airways and Exploration with Type A Overprint in Red, a mint never hinged single showing the "small v" variety, occurring once only in every pane, fine-very fine. Catalogue value is for a regular stamp only. (Image)

Unitrade $ 525

1926 5c Patricia Airways and Exploration with Ascending Type B Overprint in Black, a mint never hinged single from upper right corner of sheet, showing the "small v" variety, occurring once only in every pane, very fine and quite fresh. Catalogue value is for a regular stamp only. (Image)

Unitrade $ 1,875

1926 5c Patricia Airways and Exploration Co. Ltd. with Ascending Type B Overprint in Black, a mint never hinged upper left corner sheet margin single, showing the bold red "$4.00 over $2.00" imprint in margin. Fresh, with only a light fingerprint on gum (mentioned for strict accuracy), and very fine. Only 200 of these stamps were ever printed. (Image)

Unitrade $ 1,875

1926 5c Patricia Airways and Exploration Co. Ltd. with Ascending Type B Overprint in Red, a mint never hinged upper left corner sheet margin single, showing the bold red "$4.00 over $2.00" imprint in margin. Fresh and very fine. Only 200 of these stamps were ever printed. (Image)

Unitrade $ 1,875

1926 5c Patricia Airways and Exploration Co. Ltd. with Descending Type B Overprint in Red, a mint never hinged upper left corner sheet margin single, showing the bold red "$4.00 over $2.00" imprint in margin. Fresh, very fine (light crease in margin, mentioned for strict accuracy) and quite rare, with only 24 stamps ever printed. Of those 24, only 3 from this position exist, this being the finest. Accompanied by a 2007 Saskatoon Stamp Centre guarantee of authenticity. (Image)

Unitrade $ 3,000

1926 (5c) Patricia Airways and Exploration Co. Ltd. with Descending Type D Overprint in Violet, a mint hinged single with "small v in vIA" variety from position 2 of the pane, fine. An extremely rare stamp which is missing from most important collections, with only 2 known (one in each of the two sheet printed). Accompanied by a 2019 Greene Foundation certificate. (Image)

Unitrade $ 4,500

1926 5c Patricia Airways and Exploration Co. Ltd. Rouletted with Descending Type B Overprint in Red, mint never hinged, with "Malformed o in Lookout" from position 7. Very fine and this variety is much scarcer in red than in other colours. Accompanied by a 2018 Greene Foundation certificate. (Image)

Unitrade $ 675

1926 5c Patricia Airways and Exploration with Type C Inverted Overprint in Red, Rouletted, an unused (no gum) sheet margin single, very fine and not often offered. (Image)

Unitrade $ 750

Yukon Airways and Explorations Co. Ltd. Reverse Large Die Proof in Black, on thick card measuring 99 x 76 mm, very fine. (Image)

Unitrade $ 450