Hi Matt,
As far as I know (i bought car and it had alarm fitted by previous owner) the only extra is an anti tilt device as the chap was a bit worried about his wheels.
This noise, as i say, is quite short, sharp and abrupt. It is nothing like the beep beep sound of arming/disarming and nothing like the sound of the alarm going off. It is fairly loud and does sound (to me) like some sort of warning.
I'm pretty sure that there's never been anything metal in the centre pocket when it makes this noise, and ther times i've had my phone in there,parked up, and it hasn't made the noise.
Is there anything i should look for in the car that would tell me if i have any extras such as the proximity sensor fitted?
Thanks a lot for your help Matt (and everyone else), hugely appreciated.
Dan