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In his studies, Gates had determined that there were recurring sets of pairings of the colour, text and design of the word "Private Post Card" and the text "Stamp Here" that most commonly were found on the Wilson cards. These pairings, which he numbered 1 through 8, are reproduced below, and supplemented by additional combinations.
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Nearly all of the Wilson postcards and envelopes show a printer's imprint on their face. The exception is the the early printing of the British Ensign WLS-001, and P-1 WLS-002, which have no imprint. When used, the imprints come in 3 types, as follows:
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The listings of varieties are split into two categories, those found on postcards, and those found on envelopes.
Wilson Patriotic Envelopes—Song Backs
Most of the patriotic envelopes were available with patriotic songs printed on the envelope back, although some are available without song backs. Based on the research of Henry Gates, there were 16 songs including the following:
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The Flag That Braved a Thousand Years
Note the omitted imprint and the added advertisement in this example

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It's Only a Bit of Bunting

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Red, White and Blue

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Two Songs: The Star Spangled Banner and The Old Union Jack
Note that 2 different imprints are found on this song back
See inscriptions Type i & Type ii

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The Star Spangled Banner

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Rule Britannia

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The Flag We Learned to Love

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Bobs

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The Maple Leaf

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O Canada, Fair Canada

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The Land of the Maple

Two Songs: The Land of the Maple and The Star Spangled Banner

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The Soldiers of the Queen

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Pass the Hat for Your Credit's
Note: An error in the attribution text "SOLDIERS BOYS" also exists

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When Johnny Canuck Comes Home

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God Save The Queen
See inscription Type v

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We're Britons None The Less Sir!

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The Old Union Jack

Kenneth Rowe has identified, in The Postal History of the Canadian Contingents, a 17th song, “We’re Britons None the Less”, as yet another envelope back, identified here as Song Back 17. The Old Union Jack used individually was unknown to Henry Gates, and is shown above as Song Back 18. Both are shown in the table above.

Rowe also noted that he knew of a single example of “When Johnny Canuck Comes Home” being printed on the back of a postcard. See the link above for examples of song backs printed on postcards, many of which were unknown unknown to Gates or Rowe.
Wilson Patriotic Envelopes—Song Back Printer's Inscription
Gates notes that the backs of the envelopes bore the text "Patriotic Envelopes, with Patriotic songs on the reverse for correspondence with our SOLDIER BOYS in South Africa, J.C. Wilson & Co., Publishers, Montreal." He notes that the words "Publishers, Montreal" may be reversed.

He also notes the inscription is omitted on Song Back No. 4, although variations have been found on Song Back No. 4 with both inscription Types ii and iii. With an additional inscription identified to Gates' initial types (labeled here as Type i and Type ii), there are 6 types as follows:

No text

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Patriotic Envelopes, with Patriotic songs on the reverse for correspondence with our SOLDIER BOYS in South Africa,
J.C. Wilson & Co., Publishers, Montreal

Note that a variety of the above inscription exists with the text “... our SOLDIERS BOYS...” with an added “S”, numbered here as inscription iia

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6 DESIGNS, 12 PATRIOTIC SONGS, J.C. WILSON & CO., MONTREAL

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Patriotic Envelopes, with Patriotic songs on the reverse for correspondence with our SOLDIER BOYS in South Africa.
Price, $3.50 per 1000. Sample 100 by mail, post paid 50 cts.
J.C. Wilson & Co., Montreal, Publishers

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“The Queen” This design is intended to show the Patriotic feelings of the Colonies towards the Mother Country. ---
J.C. Wilson & Co., Paper Makers, Montreal, Publishers. Design No. 10
(shown on 2 lines below for greater readability)

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These envelopes supplied gratis, for free distribution to Canadian Soldiers in, and going to, South Africa,
by Nelson Lodge, Sons of England, Almonte, Ont. Canada
J.C. Wilson & Co., Montreal, Publishers