I have a fair idea where it's come from, and it's an awkward situation.
I do remember someone saying to me they had a pure white kitten, around September time, and that they were going to keep it in. However this little thing looks too rough for a cat that's supposedly been kept in.
I know I should ask them but if they say it's theirs, then what do i say.

Do I tell them off for not caring for it properly.
I would have to, and that's pretty confrontational isn't it.
Would it be better to take it to some official cat charity and tell them where I think the cats from, and maybe they could ask the owners if they still want the cat. Oh I dunno what's best.

I'm gonna have to ask them aren't I!