Canada 1972 International Underpaid Postage Due Cover to Stanley Gibbons (London, UK)

A fascinating and highly collectible piece of international postal history showing underpaid mail from Canada to the United Kingdom, treated with British postage due markings and adhesive stamps upon arrival.

Item Specifics & Condition:
* Origin: Ottawa, Ontario, Canada (Sent by Mrs. Leonard Pike)
* Destination: Stanley Gibbons Ltd (Shop), 391 Strand, London W.C.2, United Kingdom
* Mailing Date: November 21, 1972
* Front Postage (Canada): Features three 1970s definitive stamps (2c, 3c, and 5c Queen Elizabeth II portrait series) cancelled by an Ottawa machine postmark.
* Underpayment Markings: Stamped with a circular "T 10/15" tax marking indicating insufficient postage for international delivery.
* British Postage Due (To Pay): Features two Great Britain "To Pay" postage due labels (1/2p and 3p values) affixed to the lower-left corner to collect the underpayment fee from the recipient.
* Reverse Side: Features a decorative 1972 Canada Christmas/Charity seal strip ("Respiratory Diseases") intact across the back flap.
* Condition: Very Good vintage condition. Light peripheral wear from transit and handling. The markings and stamps are crisp, bold, and entirely legible. Completely intact envelope structure.

Please review the high-resolution front and back photos to evaluate the condition and postmark clarity for your collection. Shipped securely to preserve postal history integrity.