Thanks both - no, it's definitely not a urine infection or crystals -
the vet has checked for both.

Also, she's not declawed. My personal view is that is no way to treat
a cat except under the most extreme of medical circumstances.

The point about the automatic box is an interesting one though. I had
assumed the 12 min delay would be enough for her not to associate the
noise and motion with her use of the box. You may well be onto
something. I have a regular box (for travelling) and may set that up
nearby and see if she expresses a preference or it helps with the
noise.

From my point of view - it's fine, she's perfectly happy and my
neighbours are patient ! But I am curious from a behavioural point of
view.

Thanks again