Are you sure it's the warehouse? There was a problem with the Forest Hill school alarm that took about month to sort out and it is still prone to going off at night for no reason, although much less often these days. There is a blue flashing light over the entrance to the school in Dacres Road when it goes off. The number for the security company is posted outside the school and I call them when it goes off. Mysteriously these false alarms don't seem to alert the police or keyholders - it's up to their sleep-deprived neighbours. The school had no idea it was going off.