Some woman in the store just now, a stranger, stared at me with that smile as if she knows who I am. That sort of look has always put me off. I don't mean that fleeting smile of greeting between passing strangers on the street; it's more like that dotty old lady who's just found a victim, smile. It's an unbreaking gaze that's almost violating in its ability to make you feel as if someone's seeing something about you, a secret, that you try most carefully to hide.