Explains vintage photography site Sussex PhotoHistory of his method:
Pointer often arranged his cats in unusual poses that mimicked human activities - a cat riding a tricycle, cats roller-skating and even a cat taking a photograph with a camera. Harry Pointer soon realised that even a relatively straight-forward cat photograph could be turned into an amusing or appealing image by adding a written caption. Pointer increased the commercial potential of his cat pictures by adding a written greeting such as "A Happy New Year" or "Very many happy returns of the day."
Photo History Sussex via Retronaut