Luckily I have a video camera watching the front and it turns out while the council workmen were strimming the grass across the road the flicked up a stone and put the window through. Thanks to the evidence I can claim my £75 excess back but it is the inconvenience of removing glass from the car for the next few years at least.
Another thing I am not happy about is the alarm did not even sound when the glass was broken so will be having a word with BMW about that.
Apologies for the crappy pic it was taken from the video camera as I was moving it down the drive out of the rain.

 
							





 Never anthropomorphise computers. They hate that.
 Never anthropomorphise computers. They hate that.
 Also found the culprit stone as well.......
 Also found the culprit stone as well.......
 )
)