3:13 PM, Southampton Row, WC1

A short man in a soiled overcoat crosses the road, toiling against the flow of people heading towards Holborn Underground Station. He bends forward, head parting the throng, with his right arm stretched out behind him as he pulls along a metal cage on wheels. It is the type that is used by supermarkets to store goods in a warehouse and from which they replenish their shelves. It is almost 6 feet tall, and is packed to capacity with partially-filled plastic bags. Many more have been tied on to the frame, and they hang like deflated balloons.