It was when our girls were little and cat crazy that we gave in and got a cat from the SPCA. I called her Puff from my vague memories of Dick and Jane and Sally and Spot and Puff. Yes, I learned to read in those books and fine books they were too.
It was Puff who taught me how to love a cat. She was young and crazy and she enchanted the entire household, including our ChowChow who went from trying to kill cats to playing a game where Puff would dodge out from corners, throw herself under him and play with his feathers (the long fur growing from the back of his legs). After Puff was run over by a car, only several months after we got her, he continued for several weeks to slow down at her favorite "pounce" corners and wait for her attack.
Most of all, Puff loved me. She slept behind my knees, she laid on my shoulder and hit my book, she threw herself at me and shamelessly demanded attention. I was enchanted, like the rest of the household. We had another couple of cats after Puff and I loved them too, though neither was up to Puff on my cat scale of perfection.
All that is a very long way of saying that I understand why Gwen Johns included her cat in so many of her paintings. If I painted, I would too.