After a two week sojourn for R&R at my mum's while I went on a trip, Rani came home today. She is much recovered, though not quite back to 100 per cent. Very roughly, off the top of my head, I'd say about 89.62.
The vet called me a week ago to say the chest infection didn't appear to be caused by an underlying condition which is a relief, so it's back to the vet this week when she's finished her antibiotics, for a final all-clear.
Update: So Dave the Vet hinted that Rani may have had bacterial pneumonia. Anyway, she's recovering well, although he detected a tiny, tiny, invisible-to-normal-human-ears Rani-cough with his stethoscope. So not fully recovered yet, and because of the half-dose antibiotics mum inadvertently had her on, he thinks it's wise to keep her on them for another three weeks. As long as she doesn't have any kind of relapse we can then assume she is fully well. Hoorah.