The ducks in St James's Park are so used to being fed bread by secret agents meeting clandestinely that they have developed their own Pavlovian reaction. Put a St James's Park duck in a laboratory cage and show it a picture of two men — one usually wearing a coat with a fur collar, the other something sombre with a scarf — and it'll look up expectantly.

Good Omens (ed. Random House, 2011) - ISBN: 9781448110230