UPDATE We got to the campus today and couldn't find the cat anywhere. Security had seen her, and said they'd heard a story about a woman living down the road with lots of cats, and that this cat always turned up with another cat. I call BS, this cat was very much alone and definitely neglected.
We looked around for ages, keeping our ears open for kitten squeals, but to no avail. We were just about to give up when she ran up to my husband! Poor thing was parched and starving - she scoffed a standard portion of kibble in next to no time and then drank and moved onto wet food. She was quite easy to get into the carrier, a bit wriggly but very friendly (got worse scratches off PuffinCat yesterday).
There is a bit of a mystery: despite looking enormous on Tuesday, DStray is definitely not pregnant, and doesn't have any milk either, so we didn't miss her kittens. She was v v dehydrated, so got a few shots to get some fluids in her. She also has a slightly torn ear and has patchy fur. The rescue lady is taking her to the vets to be scanned for a chip and be checked up. Unfortunately, she has no suitable pens available for a normal, non-pg cat. The rescue lady is waiting for someone to trap a very sick cat that's been visiting a house, the ordinary pen is reserved for him. If this cat is trapped and taken to the rescue, and DStray is not chipped, she will be neutered and then have to be returned to where we found her. We don't like the thought of this at all (though we understand needs must), so we are seriously thinking about taking her on if it gets to this. Need to check with the landlady whether we can have two cats, but as PuffinCat has schmoozed her repeatedly I have good hopes :)
CPL said PuffinCat should be an only, but we don't really know why. Can we risk it? So... Any advice on how to introduce a new cat welcome :)