Perhaps Mr Widgery could set his mind to the design flaws in the fire alarm system installed at Imperial College London. The alarms are not triggered by cigarette smoke . . . unless the naughty students have squeezed a little cannabis in among the tobacco. If so, the sensors are triggered by its ionising fumes. Installing the new system has caused alarming revelations, with 15 students caught smoking cannabis in one week in May alone, reports Felix, the college's student paper.