Seriously though, this makes me wonder how long the postcard publishers kept their images in use? Forty years does seem to be a long time.
Maybe this will help explain it:
The company Valentine & Sons was established in 1851 by Mr James Valentine (1814-1879), the son of Mr John Valentine, engineer of wood blocks for linen printing, Dundee. The firm began as early exponents of photography, became pioneers in the postcard industry and later developed the production of greetings cards, novelties, calendars and illustrated children's books.
James Valentine began in business aged 17 as an engraver. He began to practice Daugerrotype photography, first as an amateur, as an aid to engraving. He was soon proficient and began to take views and portraits in c.1850. He went to Paris to train under M. Bulow, one of the most skillful photographers in that city. On his return to Dundee he set up a studio in the High Street. He received a commission from the Queen to photograph a set of 40 views of Highland scenery and in 1868 was appointed as the Royal Photographer.
James Valentine's sons were both early to develop skills in photography and by 1879 they were in great demand, having grown into one of the largest establishments in the country. In 1897 the government allowed correspondence to be written on the reverse of a postcard. This coincided with Valentine's success in collotype printing, a lithographic technique which mechanically reproduced images for printing as postcards. By the end of the century, Valentines had established the perfect method for cheap reproduction of postcards. They were also able to use their immense collection of topographical negatives to issue series after series of scenes from throughout Britain.
By the early 1900s they also had a growing trade in Christmas cards and children's books and had begun to publish fancy cards. In 1908 they became the official postcard publishers for the international Franco-British exhibition at the White City, and began to publish exhibition cards which are noted for their high quality of design. By the time of the First World War they had become a world-wide name with office branches in Canada, South Africa, Australia, America and Norway. In the 1920s they expanded their trade in Christmas cards and calendars and then in greetings cards which forms the basis of their business today. In 1963 the company became a subsidiary of John Waddington Ltd.