So.
My neighbours have a cat. They usually leave a back window open, which she can get out of but doesn't seem to be able to get back into (it's on the first (not ground) floor). I presume they leave her water and food inside, although I have no way of knowing for sure. I'm pretty sure they don't leave her water and food outside. That would be fine, except she can't get back in. I can understand not leaving food, because rats would just eat it and cause problems, but not leaving water is mean. I suspect they don't have a litterbox inside for her, which is why the window is left open for her to get out, but I don't know for sure.
Late afternoon or evening she is always hanging around our place, and if I see her out there and it's been hot I always let her come in for a drink of water. If I'm doing food preparation at the time then she looks at me beseechingly, in that way that cats do when they think there might be a bit of fish in it for them.
She's thin. She's very thin. I know cats ARE thin, generally, but she's worryingly thin. She's also worryingly wary of people and contact, much more than she used to be; she was quite an affectionate creature when the neighbours brought her home in 2005, six months old.
Lately I've been succumbing and giving her a bit of fish (tuna in springwater) if I'm having any. She seems very grateful and rubs up against my legs and even purrs a bit. She eats fast and wants more. She's hungry.
I have NO direct evidence that the neighbours are mistreating this animal in any way. I don't like these neighbours much; they smoke in the garden, and when they replaced their fence they took some of our garden, and I get upset when people smoke and have pets because it is bad for the pets, who have no way to complain.
Is this a "talk to the neighbours" situation, or a "feed the cat once in a while" situation, or a "call the RSPCA" situation? I have no idea. Mitsy is definitely better off there than she would be in a cat home, so I don't want her taken away. I'm loathe to confront the neighbours about it as I'm not the best neighbour myself sometimes and I don't want to be on the receiving end of a defensive response.