Someone now says they have spoken to several experts in meteorites and they both say it's very likely a meteorite, golf ball size or even a bit larger, hit on some pointy edge.
That's where my thinking is heading as well. Terminal velocity considerations mean there would have to be a larger mass involved than that of a micrometeorite. The penetration and dimple out the back suggests to me that the impact velocity was significant - and that tends to make the idea of a terrestrially launched object somewhat improbable.
The other thing that, to me at least, excludes the possibility of a cricket ball (unless it had a sharp piece of something like blue metal (gravel) embedded into it) is the actual damage to the glass itself. By looking closely at the centre, we see an area less than 1mm across where the glass is all white. To me, this is where the glass has been crushed - by direct and intense
pressure from the initial point of contact of the object. All other fracturing radiates out with increasing size of the glass pieces, indicating less intense forces (if any) and the fundamental radial fracture pattern of tempered glass.

The final thing which gives me more confidence in the meteorite idea is that, if you don't know what to look for, the offending object will just be another rock in the back yard.