Versions of this joke were published in New Zealand and Australian (and perhaps British?) newspapers from at least 1907 until 1935.
In some the landlady’s cat was implicated; in others the old soldier just mentioned that they were in differing, but unspecified, regiments.
New Finds

Rex; circa 1967-8.
Probable General Plastic buttons, 1940s
Cards printed with the ‘vine-leaf’ design, including some marked “Made in Australia” and one bearing the ‘Beauclaire Rose’ design were sold in the ?1930-40s. It is a fair bet they were made by General Plastics P/L, and/or their predecessors Herrman Co. or O.C. Rheuben & Co.
i have found some loose buttons that match:
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