If she was in Tescos, surely they have CCTV of the car park?
What's the point in stickying this?
So if we drive off and suddenly find our cat's missing we can go 'oh so someone's nicked it while I was shopping, like in Martz thread'.
I don't see the point in stickying the post? It sucks that this has happened, but get a claim in is all you/she can do.
What possible evasive action can we take to avoid this sort of weird theft? What should we do if we see the theft in progress? Go and talk to these nutters? If you live near Heathrow it probably explains why your insurance premiums are so high.

It'd be like stickying a thread about making sure you put your handbrake on, because my car rolled off down a hill when I didn't put mine on well enough.... although let's face it - at least it's possible to do something about that problem!