Defibrillators on site?

Us monkeys aren't experts on such things but I got myself thinking ...

Defibrillators are a fantastic piece of kit and have saved many lives and I think its really good that the CC have seen fit to issue all sites with these but apparently these are locked away in the office, which seems wrong to me! 

Considering that every second counts in such an emergency where this equipment would be useful   shouldn't they be in a place that is available and accesible to anyone on site?