It was a black-and-white photograph my father had taken many years ago of an elderly street-cleaner with a white goatee beard, wrinkled socks and down-at-heel shoes. Crumpled work trousers, work gloves, a woollen beret. The camera is low, on the pavement: Dad must have crouched in the road to take it. The man is bending down, his besom of birch twigs propped against his side. He has taken off one of his gloves, and between the thumb and first finger of his bare right hand he is offering a crumb of bread to a sparrow on the kerbstone. The sparrow is caught midhop at exactly at the moment it takes the crumb from his fingers. And the expression on the man’s face is suffused with joy. He is wearing the face of an angel.