A very jolly birthday

This vintage postcard features a photo of a tabby cat, with a message "To wish you a very jolly birthday" along the top. At the bottom of is a poem that reads "Lots of good things for your birthday, That's what I'm wishing for you, Sunshine and gladness and laughter, Happiness all the day through."

On the back is no stamp or postmark, but a pencil message in rather childlike handwriting that says "With best love from Edna xxxxxxxx".

The back also has a printers mark that reads "The 'Windsor' series copyright", with the number 4621-3 in the corner on the front of the postcard. However I couldn't find any information about this series that would help me date it.