Turn on the left hand switch and leave it on for ten minutes before turning it off. Then turn on the middle switch and go into the light bulb room straight away. Touch each light bulb one by one. The warm light bulb will be the one that was switched on for ten minutes, so that is controlled by the left hand switch. The middle switch controls the bulb that is switched on. And the bulb that is neither ‘on’ or warm is controlled by the right hand switch. Easy!
