We stayed once before in Chiswick and fell in love with the neighborhood, so we searched primarily in Chiswick. Cassie's hideaway was perfect for us. It's small - essentially a small studio apartment. If you're planning on fixing your own meals, this is NOT the place for that. There's a microwave and very small kitchen area. But if you're not planning on cooking or baking, this is a great place. Within 5 minutes of walking, there are restaurants, coffee shops, markets, and lots of (mostly) small shops that offer everything. The Underground station is less than 10 minutes walk away, and there are lots of busses as well.
The room is quiet and clean with a very nice garden attached. It's not soundproof, but that wasn't a big issue, because the neighbors are quite quiet, as far as we could tell.
We didn't meet Cassie, but we met her son and daughter-in-law, and they were very kind and helpful. I'm sure Cassie is the same (education begins at home...).
I don't know when we'll be back in London, but when that happens, we will certainly try to stay here again.