In my experience - NO!
Last night I had my passenger window smashed and my navigation system stolen - when I inspected the car the alarm LED was still flashing the armed state.
I opened the car and re-locked it - alarm went through its usual arming sequence for 10 seconds, I then reached through the window and bloody nothing.
Alarm is supposed to have parometric and volumetric alarms.
Thanks landrover for giving me an alarm that is as useful as a chocolate fireguard.
I suggest you all check yours!