Coming round a corner I felt the 'ping' of a stone exiting from beneath the rear tyre...
... followed shortly by the sound of breaking glass. I looked back over my shoulder and - yep - it just *had* to be the windscreen of the Porsche 911
The car was parked in residents parking, so I knocked on a few doors but no-one knew who it belonged to. I left a message on the car and popped into the police station to report (I know I don't have to but I am an honest person).
Just waiting for the owner to call. Hopefully they'll be full comp and it will be covered by their insurance. If not, my insurers will have to fork out.