I am so old that I remember the Cat's Meat shop in my London suburb. Child-me was puzzled
Later, the following dawned on me:
For decades and decades, horse-power was the method used to transport goods, whether at the brewery end of things, the dairy end of things, or the Steptoe and Son level - and everything in between! Imagine how many horses there must have been in London.
Even in the 50's, where I lived the milk was still delivered daily on a horse-drawn milk float, and the greengrocer came round at certain times each week with a horse-drawn flat bed cart displaying his wares.
London knacker's yards had to do something with the horse corpses. Horse-hair, and bones for glue, were two of the ways of making a bob or two out of them, but you can't sell horse meat to the British, even if it is young and tender, which this definitely was not. Thus the cat slaves of the time were the market for the meat.
I don't suppose the cats minded one bit. And I like the idea of recycling horses into cats